Kernel/vfs/mmap.c

   1 /*
   2  * Acess2 Kernel VFS
   3  * - By John Hodge (thePowersGang)
   4  *
   5  * mmap.c
   6  * - VFS_MMap support
   7  */
   8 #define DEBUG   0
   9 #include <acess.h>
  10 #include <vfs.h>
  11 #include <vfs_ext.h>
  12 #include <vfs_int.h>
  13
  14 #define MMAP_PAGES_PER_BLOCK    16
  15
  16 // === STRUCTURES ===
  17 typedef struct sVFS_MMapPageBlock       tVFS_MMapPageBlock;
  18 struct sVFS_MMapPageBlock
  19 {
  20         tVFS_MMapPageBlock      *Next;
  21         Uint64  BaseOffset;     // Must be a multiple of MMAP_PAGES_PER_BLOCK*PAGE_SIZE
  22         tPAddr  PhysAddrs[MMAP_PAGES_PER_BLOCK];
  23 };
  24
  25 // === CODE ===
  26 void *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset)
  27 {
  28         tVFS_Handle     *h;
  29         tVAddr  mapping_dest, mapping_base;
  30          int    npages, pagenum;
  31         tVFS_MMapPageBlock      *pb, *prev;
  32
  33         ENTER("pDestHint iLength xProtection xFlags xFD XOffset", DestHint, Length, Protection, Flags, FD, Offset);
  34
  35         if( Flags & MMAP_MAP_ANONYMOUS )
  36                 Offset = (tVAddr)DestHint & 0xFFF;
  37
  38         npages = ((Offset & (PAGE_SIZE-1)) + Length + (PAGE_SIZE - 1)) / PAGE_SIZE;
  39         pagenum = Offset / PAGE_SIZE;
  40
  41         mapping_base = (tVAddr)DestHint;
  42         mapping_dest = mapping_base & ~(PAGE_SIZE-1);
  43
  44         // TODO: Locate space for the allocation
  45
  46         // Handle anonymous mappings
  47         if( Flags & MMAP_MAP_ANONYMOUS )
  48         {
  49                 size_t  ofs = 0;
  50                 LOG("%i pages anonymous to %p", npages, mapping_dest);
  51                 for( ; npages --; mapping_dest += PAGE_SIZE, ofs += PAGE_SIZE )
  52                 {
  53                         if( MM_GetPhysAddr(mapping_dest) ) {
  54                                 // TODO: Set flags to COW if needed (well, if shared)
  55                                 MM_SetFlags(mapping_dest, MM_PFLAG_COW, MM_PFLAG_COW);
  56                                 LOG("clear from %p, %i bytes", (void*)(mapping_base + ofs),
  57                                         PAGE_SIZE - (mapping_base & (PAGE_SIZE-1))
  58                                         );
  59                                 memset( (void*)(mapping_base + ofs), 0, PAGE_SIZE - (mapping_base & (PAGE_SIZE-1)));
  60                         }
  61                         else {
  62                                 LOG("New empty page");
  63                                 // TODO: Map a COW zero page instead
  64                                 if( !MM_Allocate(mapping_dest) ) {
  65                                         // TODO: Error
  66                                         Log_Warning("VFS", "VFS_MMap: Anon alloc to %p failed", mapping_dest);
  67                                 }
  68                                 memset((void*)mapping_dest, 0, PAGE_SIZE);
  69                                 LOG("Anon map to %p", mapping_dest);
  70                         }
  71                 }
  72                 LEAVE_RET('p', (void*)mapping_base);
  73         }
  74
  75         h = VFS_GetHandle(FD);
  76         if( !h || !h->Node )    LEAVE_RET('n', NULL);
  77
  78         LOG("h = %p", h);
  79
  80         Mutex_Acquire( &h->Node->Lock );
  81
  82         // Search for existing mapping for each page
  83         // - Sorted list of 16 page blocks
  84         for(
  85                 pb = h->Node->MMapInfo, prev = NULL;
  86                 pb && pb->BaseOffset + MMAP_PAGES_PER_BLOCK < pagenum;
  87                 prev = pb, pb = pb->Next
  88                 );
  89
  90         LOG("pb = %p, pb->BaseOffset = %X", pb, pb ? pb->BaseOffset : 0);
  91
  92         // - Allocate a block if needed
  93         if( !pb || pb->BaseOffset > pagenum )
  94         {
  95                 void    *old_pb = pb;
  96                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
  97                 if(!pb) {
  98                         Mutex_Release( &h->Node->Lock );
  99                         LEAVE_RET('n', NULL);
 100                 }
 101                 pb->Next = old_pb;
 102                 pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
 103                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 104                 if(prev)
 105                         prev->Next = pb;
 106                 else
 107                         h->Node->MMapInfo = pb;
 108         }
 109
 110         // - Map (and allocate) pages
 111         while( npages -- )
 112         {
 113                 if( MM_GetPhysAddr(mapping_dest) == 0 )
 114                 {
 115                         if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
 116                         {
 117                                 if( h->Node->MMap )
 118                                         h->Node->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
 119                                 else
 120                                 {
 121                                          int    read_len;
 122                                         // Allocate pages and read data
 123                                         if( MM_Allocate(mapping_dest) == 0 ) {
 124                                                 // TODO: Unwrap
 125                                                 Mutex_Release( &h->Node->Lock );
 126                                                 LEAVE('n');
 127                                                 return NULL;
 128                                         }
 129                                         // TODO: Clip read length
 130                                         read_len = h->Node->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
 131 //                                      if( read_len != PAGE_SIZE ) {
 132 //                                              memset( (void*)(mapping_dest+read_len), 0, PAGE_SIZE-read_len );
 133 //                                      }
 134                                 }
 135                                 pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
 136                                 MM_SetPageNode( pb->PhysAddrs[pagenum - pb->BaseOffset], h->Node );
 137                                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 138                                 LOG("Read and map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 139                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 140                         }
 141                         else
 142                         {
 143                                 MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
 144                                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 145                                 LOG("Cached map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 146                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 147                         }
 148                         h->Node->ReferenceCount ++;
 149
 150                         // Set flags
 151                         if( !(Protection & MMAP_PROT_WRITE) ) {
 152                                 MM_SetFlags(mapping_dest, MM_PFLAG_RO, MM_PFLAG_RO);
 153                         }
 154                         else {
 155                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 156                         }
 157
 158                         if( Protection & MMAP_PROT_EXEC ) {
 159                                 MM_SetFlags(mapping_dest, MM_PFLAG_EXEC, MM_PFLAG_EXEC);
 160                         }
 161                         else {
 162                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_EXEC);
 163                         }
 164                 }
 165                 else
 166                 {
 167                         LOG("Flag update on %p", mapping_dest);
 168                         if( (MM_GetFlags(mapping_dest) & MM_PFLAG_RO) && (Protection & MMAP_PROT_WRITE) )
 169                         {
 170                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 171                         }
 172                 }
 173                 if( Flags & MMAP_MAP_PRIVATE )
 174                         MM_SetFlags(mapping_dest, MM_PFLAG_COW, MM_PFLAG_COW);
 175                 pagenum ++;
 176                 mapping_dest += PAGE_SIZE;
 177
 178                 // Roll on to next block if needed
 179                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
 180                 {
 181                         if( pb->Next && pb->Next->BaseOffset == pagenum )
 182                                 pb = pb->Next;
 183                         else
 184                         {
 185                                 tVFS_MMapPageBlock      *oldpb = pb;
 186                                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
 187                                 pb->Next = oldpb->Next;
 188                                 pb->BaseOffset = pagenum;
 189                                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 190                                 oldpb->Next = pb;
 191                         }
 192                         pagenum = 0;
 193                 }
 194         }
 195
 196         Mutex_Release( &h->Node->Lock );
 197
 198         LEAVE('p', mapping_base);
 199         return (void*)mapping_base;
 200 }
 201
 202 int VFS_MUnmap(void *Addr, size_t Length)
 203 {
 204         return 0;
 205 }