KernelLand/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 // === PROTOTYPES ===
  26 //void  *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset);
  27 void    *VFS_MMap_Anon(void *Destination, size_t Length, Uint FlagsSet, Uint FlagsMask);
  28 //int   VFS_MUnmap(void *Addr, size_t Length);
  29
  30 // === CODE ===
  31 void *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset)
  32 {
  33         tVAddr  mapping_base;
  34          int    npages, pagenum;
  35         tVFS_MMapPageBlock      *pb, *prev;
  36
  37         ENTER("pDestHint iLength xProtection xFlags xFD XOffset", DestHint, Length, Protection, Flags, FD, Offset);
  38
  39         if( Flags & MMAP_MAP_ANONYMOUS )
  40                 Offset = (tVAddr)DestHint & 0xFFF;
  41
  42         npages = ((Offset & (PAGE_SIZE-1)) + Length + (PAGE_SIZE - 1)) / PAGE_SIZE;
  43         pagenum = Offset / PAGE_SIZE;
  44
  45         mapping_base = (tVAddr)DestHint;
  46         tPage   *mapping_dest = (void*)(mapping_base & ~(PAGE_SIZE-1));
  47
  48         if( DestHint == NULL )
  49         {
  50                 // TODO: Locate space for the allocation
  51                 LEAVE('n');
  52                 return NULL;
  53         }
  54
  55         // Handle anonymous mappings
  56         if( Flags & MMAP_MAP_ANONYMOUS )
  57         {
  58                 // TODO: Comvert \a Protection into a flag set
  59                 void    *ret = VFS_MMap_Anon((void*)mapping_base, Length, 0, 0);
  60                 LEAVE_RET('p', ret);
  61         }
  62
  63         tVFS_Handle *h = VFS_GetHandle(FD);
  64         if( !h || !h->Node )    LEAVE_RET('n', NULL);
  65
  66         LOG("h = %p", h);
  67
  68         Mutex_Acquire( &h->Node->Lock );
  69
  70         // Search for existing mapping for each page
  71         // - Sorted list of 16 page blocks
  72         for(
  73                 pb = h->Node->MMapInfo, prev = NULL;
  74                 pb && pb->BaseOffset + MMAP_PAGES_PER_BLOCK < pagenum;
  75                 prev = pb, pb = pb->Next
  76                 )
  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 = calloc( 1, 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                 if(prev)
  93                         prev->Next = pb;
  94                 else
  95                         h->Node->MMapInfo = pb;
  96         }
  97
  98         // - Map (and allocate) pages
  99         while( npages -- )
 100         {
 101                 if( MM_GetPhysAddr( mapping_dest ) == 0 )
 102                 {
 103                         if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
 104                         {
 105                                 tVFS_NodeType   *nt = h->Node->Type;
 106                                 if( !nt )
 107                                 {
 108                                         // TODO: error
 109                                 }
 110                                 else if( nt->MMap )
 111                                         nt->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest);
 112                                 else
 113                                 {
 114                                          int    read_len;
 115                                         // Allocate pages and read data
 116                                         if( MM_Allocate(mapping_dest) == 0 ) {
 117                                                 // TODO: Unwrap
 118                                                 Mutex_Release( &h->Node->Lock );
 119                                                 LEAVE('n');
 120                                                 return NULL;
 121                                         }
 122                                         // TODO: Clip read length
 123                                         read_len = nt->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE,
 124                                                 mapping_dest, 0);
 125                                         // TODO: This was commented out, why?
 126                                         if( read_len != PAGE_SIZE ) {
 127                                                 memset( (char*)mapping_dest + read_len, 0, PAGE_SIZE-read_len );
 128                                         }
 129                                 }
 130                                 pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
 131                                 MM_SetPageNode( pb->PhysAddrs[pagenum - pb->BaseOffset], h->Node );
 132                                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 133                                 LOG("Read and map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 134                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 135                         }
 136                         else
 137                         {
 138                                 MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
 139                                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 140                                 LOG("Cached map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 141                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 142                         }
 143                         h->Node->ReferenceCount ++;
 144
 145                         // Set flags
 146                         if( !(Protection & MMAP_PROT_WRITE) ) {
 147                                 MM_SetFlags(mapping_dest, MM_PFLAG_RO, MM_PFLAG_RO);
 148                         }
 149                         else {
 150                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 151                         }
 152
 153                         if( Protection & MMAP_PROT_EXEC ) {
 154                                 MM_SetFlags(mapping_dest, MM_PFLAG_EXEC, MM_PFLAG_EXEC);
 155                         }
 156                         else {
 157                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_EXEC);
 158                         }
 159                 }
 160                 else
 161                 {
 162                         LOG("Flag update on %p", mapping_dest);
 163                         if( (MM_GetFlags(mapping_dest) & MM_PFLAG_RO) && (Protection & MMAP_PROT_WRITE) )
 164                         {
 165                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 166                         }
 167                 }
 168                 if( Flags & MMAP_MAP_PRIVATE )
 169                         MM_SetFlags(mapping_dest, MM_PFLAG_COW, MM_PFLAG_COW);
 170                 pagenum ++;
 171                 mapping_dest ++;
 172
 173                 // Roll on to next block if needed
 174                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
 175                 {
 176                         if( pb->Next && pb->Next->BaseOffset == pagenum )
 177                                 pb = pb->Next;
 178                         else
 179                         {
 180                                 tVFS_MMapPageBlock      *oldpb = pb;
 181                                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
 182                                 pb->Next = oldpb->Next;
 183                                 pb->BaseOffset = pagenum;
 184                                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 185                                 oldpb->Next = pb;
 186                         }
 187                 }
 188         }
 189
 190         Mutex_Release( &h->Node->Lock );
 191
 192         LEAVE('p', mapping_base);
 193         return (void*)mapping_base;
 194 }
 195
 196 void *VFS_MMap_Anon(void *Destination, size_t Length, Uint FlagsSet, Uint FlagsMask)
 197 {
 198         size_t  ofs = (tVAddr)Destination & (PAGE_SIZE-1);
 199         tPage   *mapping_dest = (void*)( (char*)Destination - ofs );
 200
 201         if( ofs > 0 )
 202         {
 203                 size_t  bytes = MIN(PAGE_SIZE - ofs, Length);
 204
 205                 // Allocate a partial page
 206                 if( MM_GetPhysAddr(mapping_dest) )
 207                 {
 208                         // Already allocated page, clear the area we're touching
 209                         ASSERT( ofs + bytes <= PAGE_SIZE );
 210
 211                         // TODO: Double check that this area isn't already zero
 212                         memset( Destination, 0, bytes );
 213
 214                         MM_SetFlags(mapping_dest, FlagsSet, FlagsMask);
 215
 216                         LOG("#1: Clear %i from %p", Length, Destination);
 217                 }
 218                 else
 219                 {
 220                         MM_AllocateZero(mapping_dest);
 221                         LOG("#1: Allocate for %p", Destination);
 222                 }
 223                 mapping_dest ++;
 224                 Length -= bytes;
 225         }
 226         while( Length >= PAGE_SIZE )
 227         {
 228                 if( MM_GetPhysAddr( mapping_dest ) )
 229                 {
 230                         // We're allocating entire pages here, so free this page and replace with a COW zero
 231                         MM_Deallocate(mapping_dest);
 232                         LOG("Replace %p with zero page", mapping_dest);
 233                 }
 234                 else
 235                 {
 236                         LOG("Allocate zero at %p", mapping_dest);
 237                 }
 238                 MM_AllocateZero(mapping_dest);
 239
 240                 mapping_dest ++;
 241                 Length -= PAGE_SIZE;
 242         }
 243         if( Length > 0 )
 244         {
 245                 ASSERT(Length < PAGE_SIZE);
 246
 247                 // Tail page
 248                 if( MM_GetPhysAddr(mapping_dest) )
 249                 {
 250                         // TODO: Don't touch page if already zero
 251                         memset( mapping_dest, 0, Length );
 252                         LOG("Clear %i in %p", Length, mapping_dest);
 253                 }
 254                 else
 255                 {
 256                         MM_AllocateZero(mapping_dest);
 257                         LOG("Anon map to %p", mapping_dest);
 258                 }
 259         }
 260
 261         return Destination;
 262 }
 263
 264 int VFS_MUnmap(void *Addr, size_t Length)
 265 {
 266         return 0;
 267 }