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_MMap_MapPage(tVFS_Node *Node, unsigned int PageNum, tVFS_MMapPageBlock *pb, void *mapping_dest, unsigned int Protection);
  29 //int   VFS_MUnmap(void *Addr, size_t Length);
  30
  31 // === CODE ===
  32 void *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset)
  33 {
  34         ENTER("pDestHint iLength xProtection xFlags xFD XOffset", DestHint, Length, Protection, Flags, FD, Offset);
  35
  36         if( Flags & MMAP_MAP_ANONYMOUS )
  37                 Offset = (tVAddr)DestHint & 0xFFF;
  38
  39         unsigned int npages = ((Offset & (PAGE_SIZE-1)) + Length + (PAGE_SIZE - 1)) / PAGE_SIZE;
  40         unsigned int pagenum = Offset / PAGE_SIZE;
  41
  42         tVAddr mapping_base = (tVAddr)DestHint;
  43
  44         if( Flags & MMAP_MAP_FIXED )
  45         {
  46                 ASSERT( (Flags & MMAP_MAP_FIXED) && DestHint != NULL );
  47                 // Keep and use the hint
  48                 // - TODO: Validate that the region pointed to by the hint is correct
  49         }
  50         else
  51         {
  52                 Log_Warning("VFS", "MMap: TODO Handle non-fixed mappings");
  53                 if( DestHint == NULL )
  54                 {
  55                         // TODO: Locate space for the allocation
  56                         Log_Warning("VFS", "Mmap: Handle NULL destination hint");
  57                         LEAVE('n');
  58                         return NULL;
  59                 }
  60         }
  61         tPage   *mapping_dest = (void*)(mapping_base & ~(PAGE_SIZE-1));
  62
  63         // Handle anonymous mappings
  64         if( Flags & MMAP_MAP_ANONYMOUS )
  65         {
  66                 // TODO: Comvert \a Protection into a flag set
  67                 void    *ret = VFS_MMap_Anon((void*)mapping_base, Length, 0, 0);
  68                 LEAVE_RET('p', ret);
  69         }
  70
  71         tVFS_Handle *h = VFS_GetHandle(FD);
  72         if( !h || !h->Node )    LEAVE_RET('n', NULL);
  73
  74         LOG("h = %p", h);
  75
  76         Mutex_Acquire( &h->Node->Lock );
  77
  78         tVFS_MMapPageBlock      *pb, **pb_pnp = (tVFS_MMapPageBlock**)&h->Node->MMapInfo;
  79         // Search for existing mapping for each page
  80         // - Sorted list of 16 page blocks
  81         for( pb = h->Node->MMapInfo; pb; pb_pnp = &pb->Next, pb = pb->Next )
  82         {
  83                 if( pb->BaseOffset + MMAP_PAGES_PER_BLOCK <= pagenum )
  84                         break;
  85         }
  86
  87         LOG("pb = %p, pb->BaseOffset = %X", pb, pb ? pb->BaseOffset : 0);
  88
  89         // - Allocate a block if needed
  90         if( !pb || pb->BaseOffset > pagenum )
  91         {
  92                 void    *old_pb = pb;
  93                 pb = calloc( 1, sizeof(tVFS_MMapPageBlock) );
  94                 if(!pb) {
  95                         Mutex_Release( &h->Node->Lock );
  96                         LEAVE_RET('n', NULL);
  97                 }
  98                 pb->Next = old_pb;
  99                 pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
 100                 *pb_pnp = pb;
 101         }
 102
 103         // - Map (and allocate) pages
 104         while( npages -- )
 105         {
 106                 ASSERTC( pagenum, >=, pb->BaseOffset );
 107                 ASSERTC( pagenum - pb->BaseOffset, <, MMAP_PAGES_PER_BLOCK );
 108                 if( MM_GetPhysAddr( mapping_dest ) == 0 )
 109                 {
 110                         LOG("Map page to %p", mapping_dest);
 111                         if( VFS_MMap_MapPage(h->Node, pagenum, pb, mapping_dest, Protection) )
 112                         {
 113                                 Mutex_Release( &h->Node->Lock );
 114                                 LEAVE('n');
 115                                 return NULL;
 116                         }
 117                 }
 118                 else
 119                 {
 120                         LOG("Flag update on %p", mapping_dest);
 121                         if( (MM_GetFlags(mapping_dest) & MM_PFLAG_RO) && (Protection & MMAP_PROT_WRITE) )
 122                         {
 123                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 124                         }
 125                 }
 126                 if( Flags & MMAP_MAP_PRIVATE ) {
 127                         // TODO: Don't allow the page to change underneath either
 128                         MM_SetFlags(mapping_dest, MM_PFLAG_COW, MM_PFLAG_COW);
 129                 }
 130                 pagenum ++;
 131                 mapping_dest ++;
 132
 133                 // Roll on to next block if needed
 134                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
 135                 {
 136                         if( !pb->Next || pb->Next->BaseOffset != pagenum )
 137                         {
 138                                 if( pb->Next )  ASSERTC(pb->Next->BaseOffset % MMAP_PAGES_PER_BLOCK, ==, 0);
 139                                 tVFS_MMapPageBlock      *newpb = malloc( sizeof(tVFS_MMapPageBlock) );
 140                                 newpb->Next = pb->Next;
 141                                 newpb->BaseOffset = pagenum;
 142                                 memset(newpb->PhysAddrs, 0, sizeof(newpb->PhysAddrs));
 143                                 pb->Next = newpb;
 144                         }
 145
 146                         pb = pb->Next;
 147                 }
 148         }
 149
 150         Mutex_Release( &h->Node->Lock );
 151
 152         LEAVE('p', mapping_base);
 153         return (void*)mapping_base;
 154 }
 155
 156 void *VFS_MMap_Anon(void *Destination, size_t Length, Uint FlagsSet, Uint FlagsMask)
 157 {
 158         size_t  ofs = (tVAddr)Destination & (PAGE_SIZE-1);
 159         tPage   *mapping_dest = (void*)( (char*)Destination - ofs );
 160
 161         if( ofs > 0 )
 162         {
 163                 size_t  bytes = MIN(PAGE_SIZE - ofs, Length);
 164
 165                 // Allocate a partial page
 166                 if( MM_GetPhysAddr(mapping_dest) )
 167                 {
 168                         // Already allocated page, clear the area we're touching
 169                         ASSERT( ofs + bytes <= PAGE_SIZE );
 170
 171                         // TODO: Double check that this area isn't already zero
 172                         memset( Destination, 0, bytes );
 173
 174                         MM_SetFlags(mapping_dest, FlagsSet, FlagsMask);
 175
 176                         LOG("#1: Clear %i from %p", Length, Destination);
 177                 }
 178                 else
 179                 {
 180                         MM_AllocateZero(mapping_dest);
 181                         LOG("#1: Allocate for %p", Destination);
 182                 }
 183                 mapping_dest ++;
 184                 Length -= bytes;
 185         }
 186         while( Length >= PAGE_SIZE )
 187         {
 188                 if( MM_GetPhysAddr( mapping_dest ) )
 189                 {
 190                         // We're allocating entire pages here, so free this page and replace with a COW zero
 191                         MM_Deallocate(mapping_dest);
 192                         LOG("Replace %p with zero page", mapping_dest);
 193                 }
 194                 else
 195                 {
 196                         LOG("Allocate zero at %p", mapping_dest);
 197                 }
 198                 MM_AllocateZero(mapping_dest);
 199
 200                 mapping_dest ++;
 201                 Length -= PAGE_SIZE;
 202         }
 203         if( Length > 0 )
 204         {
 205                 ASSERT(Length < PAGE_SIZE);
 206
 207                 // Tail page
 208                 if( MM_GetPhysAddr(mapping_dest) )
 209                 {
 210                         // TODO: Don't touch page if already zero
 211                         memset( mapping_dest, 0, Length );
 212                         LOG("Clear %i in %p", Length, mapping_dest);
 213                 }
 214                 else
 215                 {
 216                         MM_AllocateZero(mapping_dest);
 217                         LOG("Anon map to %p", mapping_dest);
 218                 }
 219         }
 220
 221         return Destination;
 222 }
 223
 224 int VFS_MMap_MapPage(tVFS_Node *Node, unsigned int pagenum, tVFS_MMapPageBlock *pb, void *mapping_dest, unsigned int Protection)
 225 {
 226         if( pb->PhysAddrs[pagenum - pb->BaseOffset] != 0 )
 227         {
 228                 MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
 229                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 230                 LOG("Cached map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 231                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 232         }
 233         else
 234         {
 235                 tVFS_NodeType   *nt = Node->Type;
 236                 if( !nt )
 237                 {
 238                         // TODO: error
 239                 }
 240                 else if( nt->MMap )
 241                         nt->MMap(Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest);
 242                 else
 243                 {
 244                          int    read_len;
 245                         // Allocate pages and read data
 246                         if( MM_Allocate(mapping_dest) == 0 ) {
 247                                 // TODO: Unwrap
 248                                 return 1;
 249                         }
 250                         // TODO: Clip read length
 251                         read_len = nt->Read(Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest, 0);
 252                         // TODO: This was commented out, why?
 253                         if( read_len != PAGE_SIZE ) {
 254                                 memset( (char*)mapping_dest + read_len, 0, PAGE_SIZE-read_len );
 255                         }
 256                 }
 257                 pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
 258                 MM_SetPageNode( pb->PhysAddrs[pagenum - pb->BaseOffset], Node );
 259                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 260                 LOG("Read and map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 261                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 262         }
 263         // TODO: Huh?
 264         Node->ReferenceCount ++;
 265
 266         // Set flags
 267         if( !(Protection & MMAP_PROT_WRITE) ) {
 268                 MM_SetFlags(mapping_dest, MM_PFLAG_RO, MM_PFLAG_RO);
 269         }
 270         else {
 271                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 272         }
 273
 274         if( Protection & MMAP_PROT_EXEC ) {
 275                 MM_SetFlags(mapping_dest, MM_PFLAG_EXEC, MM_PFLAG_EXEC);
 276         }
 277         else {
 278                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_EXEC);
 279         }
 280
 281         return 0;
 282 }
 283
 284 int VFS_MUnmap(void *Addr, size_t Length)
 285 {
 286         return 0;
 287 }