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