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 #include <mm_virt.h>    // MM_USER_MAX
  14
  15 #define MMAP_PAGES_PER_BLOCK    16
  16
  17 // === STRUCTURES ===
  18 typedef struct sVFS_MMapPageBlock       tVFS_MMapPageBlock;
  19 struct sVFS_MMapPageBlock
  20 {
  21         tVFS_MMapPageBlock      *Next;
  22         Uint64  BaseOffset;     // Must be a multiple of MMAP_PAGES_PER_BLOCK*PAGE_SIZE
  23         tPAddr  PhysAddrs[MMAP_PAGES_PER_BLOCK];
  24 };
  25
  26 // === PROTOTYPES ===
  27 //void  *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset);
  28 void    *VFS_MMap_Anon(void *Destination, size_t Length, Uint FlagsSet, Uint FlagsMask);
  29 int     VFS_MMap_MapPage(tVFS_Node *Node, unsigned int PageNum, tVFS_MMapPageBlock *pb, void *mapping_dest, unsigned int Protection);
  30 //int   VFS_MUnmap(void *Addr, size_t Length);
  31 bool    _range_free(const tPage *Base, Uint NumPages);
  32
  33 // === CODE ===
  34 void *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset)
  35 {
  36         ENTER("pDestHint xLength xProtection xFlags xFD XOffset", DestHint, Length, Protection, Flags, FD, Offset);
  37
  38         if( Flags & MMAP_MAP_ANONYMOUS )
  39                 Offset = (tVAddr)DestHint & 0xFFF;
  40
  41         unsigned int npages = ((Offset & (PAGE_SIZE-1)) + Length + (PAGE_SIZE - 1)) / PAGE_SIZE;
  42         unsigned int pagenum = Offset / PAGE_SIZE;
  43         LOG("npages=%u,pagenum=%u", npages, pagenum);
  44
  45         tVAddr mapping_base = (tVAddr)DestHint;
  46
  47         if( Flags & MMAP_MAP_FIXED )
  48         {
  49                 ASSERT( (Flags & MMAP_MAP_FIXED) && DestHint != NULL );
  50                 // Keep and use the hint
  51                 // - TODO: Validate that the region pointed to by the hint is correct
  52         }
  53         else
  54         {
  55                 Log_Warning("VFS", "MMap: TODO Handle non-fixed mappings");
  56
  57                 // Locate a free location in the address space (between brk and MM_USER_MAX)
  58                 // TODO: Prefer first location after DestHint, but can go below
  59
  60                 // Search downwards from the top of user memory
  61                 mapping_base = 0;
  62                 for( tPage *dst = (tPage*)MM_USER_MAX - npages; dst > (tPage*)PAGE_SIZE; dst -- )
  63                 {
  64                         if( _range_free(dst, npages) ) {
  65                                 mapping_base = (tVAddr)dst;
  66                                 break;
  67                         }
  68                 }
  69                 if( mapping_base == 0 )
  70                 {
  71                         Log_Warning("VFS", "MMap: Out of address space");
  72                         errno = ENOMEM;
  73                         LEAVE('n');
  74                         return NULL;
  75                 }
  76         }
  77         tPage   *mapping_dest = (void*)(mapping_base & ~(PAGE_SIZE-1));
  78
  79         if( !_range_free(mapping_dest, npages) )
  80         {
  81                 LOG("Specified range is not free");
  82                 //errno = EINVAL;
  83                 //LEAVE('n');
  84                 //return NULL;
  85                 Log_Warning("VFS", "MMap: Overwriting/replacing maps at %p+%x", mapping_base, Length);
  86         }
  87
  88         // Handle anonymous mappings
  89         if( Flags & MMAP_MAP_ANONYMOUS )
  90         {
  91                 // TODO: Comvert \a Protection into a flag set
  92                 void    *ret = VFS_MMap_Anon((void*)mapping_base, Length, 0, 0);
  93                 LEAVE_RET('p', ret);
  94         }
  95
  96         tVFS_Handle *h = VFS_GetHandle(FD);
  97         if( !h || !h->Node )    LEAVE_RET('n', NULL);
  98
  99         LOG("h = %p", h);
 100
 101         Mutex_Acquire( &h->Node->Lock );
 102
 103         tVFS_MMapPageBlock      *pb, **pb_pnp = (tVFS_MMapPageBlock**)&h->Node->MMapInfo;
 104         // Search for existing mapping for each page
 105         // - Sorted list of 16 page blocks
 106         for( pb = h->Node->MMapInfo; pb; pb_pnp = &pb->Next, pb = pb->Next )
 107         {
 108                 if( pb->BaseOffset + MMAP_PAGES_PER_BLOCK > pagenum )
 109                         break;
 110         }
 111
 112         LOG("pb = %p, pb->BaseOffset = %X", pb, pb ? pb->BaseOffset : 0);
 113
 114         // - Allocate a block if needed
 115         if( !pb || pb->BaseOffset > pagenum )
 116         {
 117                 void    *old_pb = pb;
 118                 pb = calloc( 1, sizeof(tVFS_MMapPageBlock) );
 119                 if(!pb) {
 120                         Mutex_Release( &h->Node->Lock );
 121                         LEAVE_RET('n', NULL);
 122                 }
 123                 pb->Next = old_pb;
 124                 pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
 125                 *pb_pnp = pb;
 126         }
 127
 128         // - Map (and allocate) pages
 129         while( npages -- )
 130         {
 131                 ASSERTC( pagenum, >=, pb->BaseOffset );
 132                 ASSERTC( pagenum - pb->BaseOffset, <, MMAP_PAGES_PER_BLOCK );
 133                 if( MM_GetPhysAddr( mapping_dest ) == 0 )
 134                 {
 135                         LOG("Map page to %p", mapping_dest);
 136                         if( VFS_MMap_MapPage(h->Node, pagenum, pb, mapping_dest, Protection) )
 137                         {
 138                                 Mutex_Release( &h->Node->Lock );
 139                                 LEAVE('n');
 140                                 return NULL;
 141                         }
 142                 }
 143                 else
 144                 {
 145                         LOG("Flag update on %p", mapping_dest);
 146                         if( (MM_GetFlags(mapping_dest) & MM_PFLAG_RO) && (Protection & MMAP_PROT_WRITE) )
 147                         {
 148                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 149                         }
 150                 }
 151                 if( Flags & MMAP_MAP_PRIVATE ) {
 152                         // TODO: Don't allow the page to change underneath either
 153                         MM_SetFlags(mapping_dest, MM_PFLAG_COW, MM_PFLAG_COW);
 154                 }
 155                 pagenum ++;
 156                 mapping_dest ++;
 157
 158                 // Roll on to next block if needed
 159                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
 160                 {
 161                         if( !pb->Next || pb->Next->BaseOffset != pagenum )
 162                         {
 163                                 if( pb->Next )  ASSERTC(pb->Next->BaseOffset % MMAP_PAGES_PER_BLOCK, ==, 0);
 164                                 tVFS_MMapPageBlock      *newpb = malloc( sizeof(tVFS_MMapPageBlock) );
 165                                 newpb->Next = pb->Next;
 166                                 newpb->BaseOffset = pagenum;
 167                                 memset(newpb->PhysAddrs, 0, sizeof(newpb->PhysAddrs));
 168                                 pb->Next = newpb;
 169                         }
 170
 171                         pb = pb->Next;
 172                 }
 173         }
 174
 175         Mutex_Release( &h->Node->Lock );
 176
 177         LEAVE('p', mapping_base);
 178         return (void*)mapping_base;
 179 }
 180
 181 void *VFS_MMap_Anon(void *Destination, size_t Length, Uint FlagsSet, Uint FlagsMask)
 182 {
 183         size_t  ofs = (tVAddr)Destination & (PAGE_SIZE-1);
 184         tPage   *mapping_dest = (void*)( (char*)Destination - ofs );
 185
 186         if( ofs > 0 )
 187         {
 188                 size_t  bytes = MIN(PAGE_SIZE - ofs, Length);
 189
 190                 // Allocate a partial page
 191                 if( MM_GetPhysAddr(mapping_dest) )
 192                 {
 193                         // Already allocated page, clear the area we're touching
 194                         ASSERT( ofs + bytes <= PAGE_SIZE );
 195
 196                         // TODO: Double check that this area isn't already zero
 197                         memset( Destination, 0, bytes );
 198
 199                         MM_SetFlags(mapping_dest, FlagsSet, FlagsMask);
 200
 201                         LOG("#1: Clear %i from %p", Length, Destination);
 202                 }
 203                 else
 204                 {
 205                         MM_AllocateZero(mapping_dest);
 206                         LOG("#1: Allocate for %p", Destination);
 207                 }
 208                 mapping_dest ++;
 209                 Length -= bytes;
 210         }
 211         while( Length >= PAGE_SIZE )
 212         {
 213                 if( MM_GetPhysAddr( mapping_dest ) )
 214                 {
 215                         // We're allocating entire pages here, so free this page and replace with a COW zero
 216                         MM_Deallocate(mapping_dest);
 217                         LOG("Replace %p with zero page", mapping_dest);
 218                 }
 219                 else
 220                 {
 221                         LOG("Allocate zero at %p", mapping_dest);
 222                 }
 223                 MM_AllocateZero(mapping_dest);
 224
 225                 mapping_dest ++;
 226                 Length -= PAGE_SIZE;
 227         }
 228         if( Length > 0 )
 229         {
 230                 ASSERT(Length < PAGE_SIZE);
 231
 232                 // Tail page
 233                 if( MM_GetPhysAddr(mapping_dest) )
 234                 {
 235                         // TODO: Don't touch page if already zero
 236                         memset( mapping_dest, 0, Length );
 237                         LOG("Clear %i in %p", Length, mapping_dest);
 238                 }
 239                 else
 240                 {
 241                         MM_AllocateZero(mapping_dest);
 242                         LOG("Anon map to %p", mapping_dest);
 243                 }
 244         }
 245
 246         return Destination;
 247 }
 248
 249 int VFS_MMap_MapPage(tVFS_Node *Node, unsigned int pagenum, tVFS_MMapPageBlock *pb, void *mapping_dest, unsigned int Protection)
 250 {
 251         if( pb->PhysAddrs[pagenum - pb->BaseOffset] != 0 )
 252         {
 253                 MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
 254                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 255                 LOG("Cached map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 256                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 257         }
 258         else
 259         {
 260                 tVFS_NodeType   *nt = Node->Type;
 261                 if( !nt )
 262                 {
 263                         // TODO: error
 264                 }
 265                 else if( nt->MMap )
 266                         nt->MMap(Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest);
 267                 else
 268                 {
 269                          int    read_len;
 270                         // Allocate pages and read data
 271                         if( MM_Allocate(mapping_dest) == 0 ) {
 272                                 // TODO: Unwrap
 273                                 return 1;
 274                         }
 275                         // TODO: Clip read length
 276                         read_len = nt->Read(Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest, 0);
 277                         // TODO: This was commented out, why?
 278                         if( read_len != PAGE_SIZE ) {
 279                                 memset( (char*)mapping_dest + read_len, 0, PAGE_SIZE-read_len );
 280                         }
 281                 }
 282                 pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
 283                 MM_SetPageNode( pb->PhysAddrs[pagenum - pb->BaseOffset], Node );
 284                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 285                 LOG("Read and map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 286                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 287         }
 288         // TODO: Huh?
 289         Node->ReferenceCount ++;
 290
 291         // Set flags
 292         if( !(Protection & MMAP_PROT_WRITE) ) {
 293                 MM_SetFlags(mapping_dest, MM_PFLAG_RO, MM_PFLAG_RO);
 294         }
 295         else {
 296                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 297         }
 298
 299         if( Protection & MMAP_PROT_EXEC ) {
 300                 MM_SetFlags(mapping_dest, MM_PFLAG_EXEC, MM_PFLAG_EXEC);
 301         }
 302         else {
 303                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_EXEC);
 304         }
 305
 306         return 0;
 307 }
 308
 309 int VFS_MUnmap(void *Addr, size_t Length)
 310 {
 311         UNIMPLEMENTED();
 312         return 0;
 313 }
 314
 315 bool _range_free(const tPage *Base, Uint NumPages)
 316 {
 317         for( int i = 0; i < NumPages; i ++ )
 318         {
 319                 if( MM_GetPhysAddr(Base + i) )
 320                 {
 321                         // Oh.
 322                         return false;
 323                 }
 324         }
 325         return true;
 326 }