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                 assert( pagenum >= pb->BaseOffset );
 102                 assert( pagenum - pb->BaseOffset < MMAP_PAGES_PER_BLOCK );
 103                 if( MM_GetPhysAddr( mapping_dest ) == 0 )
 104                 {
 105                         if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
 106                         {
 107                                 tVFS_NodeType   *nt = h->Node->Type;
 108                                 if( !nt )
 109                                 {
 110                                         // TODO: error
 111                                 }
 112                                 else if( nt->MMap )
 113                                         nt->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest);
 114                                 else
 115                                 {
 116                                          int    read_len;
 117                                         // Allocate pages and read data
 118                                         if( MM_Allocate(mapping_dest) == 0 ) {
 119                                                 // TODO: Unwrap
 120                                                 Mutex_Release( &h->Node->Lock );
 121                                                 LEAVE('n');
 122                                                 return NULL;
 123                                         }
 124                                         // TODO: Clip read length
 125                                         read_len = nt->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE,
 126                                                 mapping_dest, 0);
 127                                         // TODO: This was commented out, why?
 128                                         if( read_len != PAGE_SIZE ) {
 129                                                 memset( (char*)mapping_dest + read_len, 0, PAGE_SIZE-read_len );
 130                                         }
 131                                 }
 132                                 pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
 133                                 MM_SetPageNode( pb->PhysAddrs[pagenum - pb->BaseOffset], h->Node );
 134                                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 135                                 LOG("Read and map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 136                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 137                         }
 138                         else
 139                         {
 140                                 MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
 141                                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 142                                 LOG("Cached map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 143                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 144                         }
 145                         h->Node->ReferenceCount ++;
 146
 147                         // Set flags
 148                         if( !(Protection & MMAP_PROT_WRITE) ) {
 149                                 MM_SetFlags(mapping_dest, MM_PFLAG_RO, MM_PFLAG_RO);
 150                         }
 151                         else {
 152                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 153                         }
 154
 155                         if( Protection & MMAP_PROT_EXEC ) {
 156                                 MM_SetFlags(mapping_dest, MM_PFLAG_EXEC, MM_PFLAG_EXEC);
 157                         }
 158                         else {
 159                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_EXEC);
 160                         }
 161                 }
 162                 else
 163                 {
 164                         LOG("Flag update on %p", mapping_dest);
 165                         if( (MM_GetFlags(mapping_dest) & MM_PFLAG_RO) && (Protection & MMAP_PROT_WRITE) )
 166                         {
 167                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 168                         }
 169                 }
 170                 if( Flags & MMAP_MAP_PRIVATE )
 171                         MM_SetFlags(mapping_dest, MM_PFLAG_COW, MM_PFLAG_COW);
 172                 pagenum ++;
 173                 mapping_dest ++;
 174
 175                 // Roll on to next block if needed
 176                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
 177                 {
 178                         if( pb->Next && pb->Next->BaseOffset == pagenum )
 179                                 pb = pb->Next;
 180                         else
 181                         {
 182                                 tVFS_MMapPageBlock      *oldpb = pb;
 183                                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
 184                                 pb->Next = oldpb->Next;
 185                                 pb->BaseOffset = pagenum;
 186                                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 187                                 oldpb->Next = pb;
 188                         }
 189                 }
 190         }
 191
 192         Mutex_Release( &h->Node->Lock );
 193
 194         LEAVE('p', mapping_base);
 195         return (void*)mapping_base;
 196 }
 197
 198 void *VFS_MMap_Anon(void *Destination, size_t Length, Uint FlagsSet, Uint FlagsMask)
 199 {
 200         size_t  ofs = (tVAddr)Destination & (PAGE_SIZE-1);
 201         tPage   *mapping_dest = (void*)( (char*)Destination - ofs );
 202
 203         if( ofs > 0 )
 204         {
 205                 size_t  bytes = MIN(PAGE_SIZE - ofs, Length);
 206
 207                 // Allocate a partial page
 208                 if( MM_GetPhysAddr(mapping_dest) )
 209                 {
 210                         // Already allocated page, clear the area we're touching
 211                         ASSERT( ofs + bytes <= PAGE_SIZE );
 212
 213                         // TODO: Double check that this area isn't already zero
 214                         memset( Destination, 0, bytes );
 215
 216                         MM_SetFlags(mapping_dest, FlagsSet, FlagsMask);
 217
 218                         LOG("#1: Clear %i from %p", Length, Destination);
 219                 }
 220                 else
 221                 {
 222                         MM_AllocateZero(mapping_dest);
 223                         LOG("#1: Allocate for %p", Destination);
 224                 }
 225                 mapping_dest ++;
 226                 Length -= bytes;
 227         }
 228         while( Length >= PAGE_SIZE )
 229         {
 230                 if( MM_GetPhysAddr( mapping_dest ) )
 231                 {
 232                         // We're allocating entire pages here, so free this page and replace with a COW zero
 233                         MM_Deallocate(mapping_dest);
 234                         LOG("Replace %p with zero page", mapping_dest);
 235                 }
 236                 else
 237                 {
 238                         LOG("Allocate zero at %p", mapping_dest);
 239                 }
 240                 MM_AllocateZero(mapping_dest);
 241
 242                 mapping_dest ++;
 243                 Length -= PAGE_SIZE;
 244         }
 245         if( Length > 0 )
 246         {
 247                 ASSERT(Length < PAGE_SIZE);
 248
 249                 // Tail page
 250                 if( MM_GetPhysAddr(mapping_dest) )
 251                 {
 252                         // TODO: Don't touch page if already zero
 253                         memset( mapping_dest, 0, Length );
 254                         LOG("Clear %i in %p", Length, mapping_dest);
 255                 }
 256                 else
 257                 {
 258                         MM_AllocateZero(mapping_dest);
 259                         LOG("Anon map to %p", mapping_dest);
 260                 }
 261         }
 262
 263         return Destination;
 264 }
 265
 266 int VFS_MUnmap(void *Addr, size_t Length)
 267 {
 268         return 0;
 269 }