Kernel/arch/x86/mm_virt.c

   1 /*
   2  * AcessOS Microkernel Version
   3  * mm_virt.c
   4  *
   5  * Memory Map
   6  * 0xE0 - Kernel Base
   7  * 0xF0 - Kernel Stacks
   8  * 0xFD - Fractals
   9  * 0xFE - Unused
  10  * 0xFF - System Calls / Kernel's User Code
  11  */
  12 #define DEBUG   1
  13 #include <common.h>
  14 #include <mm_phys.h>
  15 #include <proc.h>
  16
  17 #define KERNEL_STACKS   0xF0000000
  18 #define KERNEL_STACK_SIZE       0x00002000
  19 #define KERNEL_STACK_END        0xFD000000
  20 #define PAGE_TABLE_ADDR 0xFD000000
  21 #define PAGE_DIR_ADDR   0xFD3F4000
  22 #define PAGE_CR3_ADDR   0xFD3F4FD0
  23 #define TMP_CR3_ADDR    0xFD3F4FD4      // Part of core instead of temp
  24 #define TMP_DIR_ADDR    0xFD3F5000      // Same
  25 #define TMP_TABLE_ADDR  0xFD400000
  26 #define HW_MAP_ADDR             0xFD800000
  27 #define HW_MAP_MAX              0xFEFF0000
  28 #define NUM_HW_PAGES    ((HW_MAP_MAX-HW_MAP_ADDR)/0x1000)
  29 #define TEMP_MAP_ADDR   0xFEFF0000      // Allows 16 "temp" pages
  30 #define NUM_TEMP_PAGES  16
  31
  32 #define PF_PRESENT      0x1
  33 #define PF_WRITE        0x2
  34 #define PF_USER         0x4
  35 #define PF_COW          0x200
  36 #define PF_PAGED        0x400
  37
  38 #define INVLPG(addr)    __asm__ __volatile__ ("invlpg (%0)"::"r"(addr))
  39
  40 // === IMPORTS ===
  41 extern Uint32   gaInitPageDir[1024];
  42 extern Uint32   gaInitPageTable[1024];
  43 extern void     Threads_SegFault(Uint Addr);
  44 extern void     Error_Backtrace(Uint eip, Uint ebp);
  45
  46 // === PROTOTYPES ===
  47 void    MM_PreinitVirtual();
  48 void    MM_InstallVirtual();
  49 void    MM_PageFault(Uint Addr, Uint ErrorCode, tRegs *Regs);
  50 void    MM_DumpTables(tVAddr Start, tVAddr End);
  51 tPAddr  MM_DuplicatePage(Uint VAddr);
  52
  53 // === GLOBALS ===
  54 tPAddr  *gaPageTable = (void*)PAGE_TABLE_ADDR;
  55 tPAddr  *gaPageDir = (void*)PAGE_DIR_ADDR;
  56 tPAddr  *gaPageCR3 = (void*)PAGE_CR3_ADDR;
  57 tPAddr  *gaTmpTable = (void*)TMP_TABLE_ADDR;
  58 tPAddr  *gaTmpDir = (void*)TMP_DIR_ADDR;
  59 tPAddr  *gTmpCR3 = (void*)TMP_CR3_ADDR;
  60  int    gilTempMappings = 0;
  61
  62 // === CODE ===
  63 /**
  64  * \fn void MM_PreinitVirtual()
  65  * \brief Maps the fractal mappings
  66  */
  67 void MM_PreinitVirtual()
  68 {
  69         gaInitPageDir[ 0 ] = 0;
  70         gaInitPageDir[ PAGE_TABLE_ADDR >> 22 ] = ((Uint)&gaInitPageDir - KERNEL_BASE) | 3;
  71 }
  72
  73 /**
  74  * \fn void MM_InstallVirtual()
  75  * \brief Sets up the constant page mappings
  76  */
  77 void MM_InstallVirtual()
  78 {
  79          int    i;
  80
  81         // --- Pre-Allocate kernel tables
  82         for( i = KERNEL_BASE>>22; i < 1024; i ++ )
  83         {
  84                 if( gaPageDir[ i ] )    continue;
  85                 // Skip stack tables, they are process unique
  86                 if( i > KERNEL_STACKS >> 22 && i < KERNEL_STACK_END >> 22) {
  87                         gaPageDir[ i ] = 0;
  88                         continue;
  89                 }
  90                 // Preallocate table
  91                 gaPageDir[ i ] = MM_AllocPhys() | 3;
  92                 INVLPG( &gaPageTable[i*1024] );
  93                 memset( &gaPageTable[i*1024], 0, 0x1000 );
  94         }
  95 }
  96
  97 /**
  98  * \fn void MM_PageFault(Uint Addr, Uint ErrorCode, tRegs *Regs)
  99  * \brief Called on a page fault
 100  */
 101 void MM_PageFault(Uint Addr, Uint ErrorCode, tRegs *Regs)
 102 {
 103         //ENTER("xAddr bErrorCode", Addr, ErrorCode);
 104
 105         // -- Check for COW --
 106         if( gaPageDir  [Addr>>22] & PF_PRESENT
 107          && gaPageTable[Addr>>12] & PF_PRESENT
 108          && gaPageTable[Addr>>12] & PF_COW )
 109         {
 110                 tPAddr  paddr;
 111                 if(MM_GetRefCount( gaPageTable[Addr>>12] & ~0xFFF ) == 1)
 112                 {
 113                         gaPageTable[Addr>>12] &= ~PF_COW;
 114                         gaPageTable[Addr>>12] |= PF_PRESENT|PF_WRITE;
 115                 }
 116                 else
 117                 {
 118                         paddr = MM_DuplicatePage( Addr );
 119                         MM_DerefPhys( gaPageTable[Addr>>12] & ~0xFFF );
 120                         gaPageTable[Addr>>12] &= PF_USER;
 121                         gaPageTable[Addr>>12] |= paddr|PF_PRESENT|PF_WRITE;
 122                 }
 123
 124                 INVLPG( Addr & ~0xFFF );
 125                 //LEAVE('-')
 126                 return;
 127         }
 128
 129         // If it was a user, tell the thread handler
 130         if(ErrorCode & 4) {
 131                 Warning("User Pagefault: Instruction at %p accessed %p", Regs->eip, Addr);
 132                 __asm__ __volatile__ ("sti");   // Restart IRQs
 133                 Threads_SegFault(Addr);
 134                 return ;
 135         }
 136
 137         // -- Check Error Code --
 138         if(ErrorCode & 8)
 139                 Warning("Reserved Bits Trashed!");
 140         else
 141         {
 142                 Warning("%s %s %s memory%s",
 143                         (ErrorCode&4?"User":"Kernel"),
 144                         (ErrorCode&2?"write to":"read from"),
 145                         (ErrorCode&1?"bad/locked":"non-present"),
 146                         (ErrorCode&16?" (Instruction Fetch)":"")
 147                         );
 148         }
 149
 150         Log("Code at %p accessed %p", Regs->eip, Addr);
 151         // Print Stack Backtrace
 152         Error_Backtrace(Regs->eip, Regs->ebp);
 153
 154         Log("gaPageDir[0x%x] = 0x%x", Addr>>22, gaPageDir[Addr>>22]);
 155         if( gaPageDir[Addr>>22] & PF_PRESENT )
 156                 Log("gaPageTable[0x%x] = 0x%x", Addr>>12, gaPageTable[Addr>>12]);
 157
 158         MM_DumpTables(0, -1);
 159
 160         Panic("Page Fault at 0x%x\n", Regs->eip);
 161 }
 162
 163 /**
 164  * \fn void MM_DumpTables(Uint Start, Uint End)
 165  * \brief Dumps the layout of the page tables
 166  */
 167 void MM_DumpTables(tVAddr Start, tVAddr End)
 168 {
 169         tVAddr  rangeStart = 0;
 170         tPAddr  expected = 0;
 171         tVAddr  curPos;
 172         Uint    page;
 173         const tPAddr    MASK = ~0xF98;
 174
 175         Start >>= 12;   End >>= 12;
 176
 177         #if 0
 178         Log("Directory Entries:");
 179         for(page = Start >> 10;
 180                 page < (End >> 10)+1;
 181                 page ++)
 182         {
 183                 if(gaPageDir[page])
 184                 {
 185                         Log(" 0x%08x-0x%08x :: 0x%08x",
 186                                 page<<22, ((page+1)<<22)-1,
 187                                 gaPageDir[page]&~0xFFF
 188                                 );
 189                 }
 190         }
 191         #endif
 192
 193         Log("Table Entries:");
 194         for(page = Start, curPos = Start<<12;
 195                 page < End;
 196                 curPos += 0x1000, page++)
 197         {
 198                 if( !(gaPageDir[curPos>>22] & PF_PRESENT)
 199                 ||  !(gaPageTable[page] & PF_PRESENT)
 200                 ||  (gaPageTable[page] & MASK) != expected)
 201                 {
 202                         if(expected) {
 203                                 Log(" 0x%08x-0x%08x => 0x%08x-0x%08x (%s%s%s%s)",
 204                                         rangeStart, curPos - 1,
 205                                         gaPageTable[rangeStart>>12] & ~0xFFF,
 206                                         (expected & ~0xFFF) - 1,
 207                                         (expected & PF_PAGED ? "p" : "-"),
 208                                         (expected & PF_COW ? "C" : "-"),
 209                                         (expected & PF_USER ? "U" : "-"),
 210                                         (expected & PF_WRITE ? "W" : "-")
 211                                         );
 212                                 expected = 0;
 213                         }
 214                         if( !(gaPageDir[curPos>>22] & PF_PRESENT) )     continue;
 215                         if( !(gaPageTable[curPos>>12] & PF_PRESENT) )   continue;
 216
 217                         expected = (gaPageTable[page] & MASK);
 218                         rangeStart = curPos;
 219                 }
 220                 if(expected)    expected += 0x1000;
 221         }
 222
 223         if(expected) {
 224                 Log("0x%08x-0x%08x => 0x%08x-0x%08x (%s%s%s%s)",
 225                         rangeStart, curPos - 1,
 226                         gaPageTable[rangeStart>>12] & ~0xFFF,
 227                         (expected & ~0xFFF) - 1,
 228                         (expected & PF_PAGED ? "p" : "-"),
 229                         (expected & PF_COW ? "C" : "-"),
 230                         (expected & PF_USER ? "U" : "-"),
 231                         (expected & PF_WRITE ? "W" : "-")
 232                         );
 233                 expected = 0;
 234         }
 235 }
 236
 237 /**
 238  * \fn tPAddr MM_Allocate(Uint VAddr)
 239  */
 240 tPAddr MM_Allocate(Uint VAddr)
 241 {
 242         tPAddr  paddr;
 243         // Check if the directory is mapped
 244         if( gaPageDir[ VAddr >> 22 ] == 0 )
 245         {
 246                 // Allocate directory
 247                 paddr = MM_AllocPhys();
 248                 if( paddr == 0 ) {
 249                         Warning("MM_Allocate - Out of Memory (Called by %p)", __builtin_return_address(0));
 250                         return 0;
 251                 }
 252                 // Map
 253                 gaPageDir[ VAddr >> 22 ] = paddr | 3;
 254                 // Mark as user
 255                 if(VAddr < MM_USER_MAX) gaPageDir[ VAddr >> 22 ] |= PF_USER;
 256
 257                 INVLPG( &gaPageDir[ VAddr >> 22 ] );
 258                 memsetd( &gaPageTable[ (VAddr >> 12) & ~0x3FF ], 0, 1024 );
 259         }
 260         // Check if the page is already allocated
 261         else if( gaPageTable[ VAddr >> 12 ] != 0 ) {
 262                 Warning("MM_Allocate - Allocating to used address (%p)", VAddr);
 263                 return gaPageTable[ VAddr >> 12 ] & ~0xFFF;
 264         }
 265
 266         // Allocate
 267         paddr = MM_AllocPhys();
 268         if( paddr == 0 ) {
 269                 Warning("MM_Allocate - Out of Memory when allocating at %p (Called by %p)",
 270                         VAddr, __builtin_return_address(0));
 271                 return 0;
 272         }
 273         // Map
 274         gaPageTable[ VAddr >> 12 ] = paddr | 3;
 275         // Mark as user
 276         if(VAddr < MM_USER_MAX) gaPageTable[ VAddr >> 12 ] |= PF_USER;
 277         // Invalidate Cache for address
 278         INVLPG( VAddr & ~0xFFF );
 279
 280         return paddr;
 281 }
 282
 283 /**
 284  * \fn void MM_Deallocate(Uint VAddr)
 285  */
 286 void MM_Deallocate(Uint VAddr)
 287 {
 288         if( gaPageDir[ VAddr >> 22 ] == 0 ) {
 289                 Warning("MM_Deallocate - Directory not mapped");
 290                 return;
 291         }
 292
 293         if(gaPageTable[ VAddr >> 12 ] == 0) {
 294                 Warning("MM_Deallocate - Page is not allocated");
 295                 return;
 296         }
 297
 298         // Dereference page
 299         MM_DerefPhys( gaPageTable[ VAddr >> 12 ] & ~0xFFF );
 300         // Clear page
 301         gaPageTable[ VAddr >> 12 ] = 0;
 302 }
 303
 304 /**
 305  * \fn tPAddr MM_GetPhysAddr(Uint Addr)
 306  * \brief Checks if the passed address is accesable
 307  */
 308 tPAddr MM_GetPhysAddr(Uint Addr)
 309 {
 310         if( !(gaPageDir[Addr >> 22] & 1) )
 311                 return 0;
 312         if( !(gaPageTable[Addr >> 12] & 1) )
 313                 return 0;
 314         return (gaPageTable[Addr >> 12] & ~0xFFF) | (Addr & 0xFFF);
 315 }
 316
 317 /**
 318  * \fn void MM_SetCR3(Uint CR3)
 319  * \brief Sets the current process space
 320  */
 321 void MM_SetCR3(Uint CR3)
 322 {
 323         __asm__ __volatile__ ("mov %0, %%cr3"::"r"(CR3));
 324 }
 325
 326 /**
 327  * \fn int MM_Map(Uint VAddr, tPAddr PAddr)
 328  * \brief Map a physical page to a virtual one
 329  */
 330 int MM_Map(Uint VAddr, tPAddr PAddr)
 331 {
 332         //ENTER("xVAddr xPAddr", VAddr, PAddr);
 333         // Sanity check
 334         if( PAddr & 0xFFF || VAddr & 0xFFF ) {
 335                 Warning("MM_Map - Physical or Virtual Addresses are not aligned");
 336                 //LEAVE('i', 0);
 337                 return 0;
 338         }
 339
 340         // Align addresses
 341         PAddr &= ~0xFFF;        VAddr &= ~0xFFF;
 342
 343         // Check if the directory is mapped
 344         if( gaPageDir[ VAddr >> 22 ] == 0 )
 345         {
 346                 gaPageDir[ VAddr >> 22 ] = MM_AllocPhys() | 3;
 347
 348                 // Mark as user
 349                 if(VAddr < MM_USER_MAX) gaPageDir[ VAddr >> 22 ] |= PF_USER;
 350
 351                 INVLPG( &gaPageTable[ (VAddr >> 12) & ~0x3FF ] );
 352                 memsetd( &gaPageTable[ (VAddr >> 12) & ~0x3FF ], 0, 1024 );
 353         }
 354         // Check if the page is already allocated
 355         else if( gaPageTable[ VAddr >> 12 ] != 0 ) {
 356                 Warning("MM_Map - Allocating to used address");
 357                 //LEAVE('i', 0);
 358                 return 0;
 359         }
 360
 361         // Map
 362         gaPageTable[ VAddr >> 12 ] = PAddr | 3;
 363         // Mark as user
 364         if(VAddr < MM_USER_MAX) gaPageTable[ VAddr >> 12 ] |= PF_USER;
 365
 366         //LOG("gaPageTable[ 0x%x ] = (Uint)%p = 0x%x",
 367         //      VAddr >> 12, &gaPageTable[ VAddr >> 12 ], gaPageTable[ VAddr >> 12 ]);
 368
 369         // Reference
 370         MM_RefPhys( PAddr );
 371
 372         //LOG("INVLPG( 0x%x )", VAddr);
 373         INVLPG( VAddr );
 374
 375         //LEAVE('i', 1);
 376         return 1;
 377 }
 378
 379 /**
 380  * \fn Uint MM_ClearUser()
 381  * \brief Clear user's address space
 382  */
 383 Uint MM_ClearUser()
 384 {
 385         Uint    i, j;
 386
 387         // Copy Directories
 388         for( i = 0; i < (MM_USER_MAX>>22); i ++ )
 389         {
 390                 // Check if directory is not allocated
 391                 if( !(gaPageDir[i] & PF_PRESENT) ) {
 392                         gaPageDir[i] = 0;
 393                         continue;
 394                 }
 395
 396
 397                 for( j = 0; j < 1024; j ++ )
 398                 {
 399                         if( gaPageTable[i*1024+j] & 1 )
 400                                 MM_DerefPhys( gaPageTable[i*1024+j] & ~0xFFF );
 401                         gaPageTable[i*1024+j] = 0;
 402                 }
 403
 404                 MM_DerefPhys( gaPageDir[i] & ~0xFFF );
 405                 gaPageDir[i] = 0;
 406                 INVLPG( &gaPageTable[i*1024] );
 407         }
 408         INVLPG( gaPageDir );
 409
 410         return *gaPageCR3;
 411 }
 412
 413 /**
 414  * \fn Uint MM_Clone()
 415  * \brief Clone the current address space
 416  */
 417 Uint MM_Clone()
 418 {
 419         Uint    i, j;
 420         Uint    page = 0;
 421         Uint    kStackBase = Proc_GetCurThread()->KernelStack - KERNEL_STACK_SIZE;
 422         void    *tmp;
 423
 424         //ENTER("");
 425
 426         // Create Directory Table
 427         *gTmpCR3 = MM_AllocPhys() | 3;
 428         INVLPG( gaTmpDir );
 429         //LOG("Allocated Directory (%x)", *gTmpCR3);
 430         memsetd( gaTmpDir, 0, 1024 );
 431
 432         // Copy Tables
 433         for(i=0;i<768;i++)
 434         {
 435                 // Check if table is allocated
 436                 if( !(gaPageDir[i] & PF_PRESENT) ) {
 437                         gaTmpDir[i] = 0;
 438                         page += 1024;
 439                         continue;
 440                 }
 441
 442                 // Allocate new table
 443                 gaTmpDir[i] = MM_AllocPhys() | (gaPageDir[i] & 7);
 444                 INVLPG( &gaTmpTable[page] );
 445                 // Fill
 446                 for( j = 0; j < 1024; j ++, page++ )
 447                 {
 448                         if( !(gaPageTable[page] & PF_PRESENT) ) {
 449                                 gaTmpTable[page] = 0;
 450                                 continue;
 451                         }
 452
 453                         // Refrence old page
 454                         MM_RefPhys( gaPageTable[page] & ~0xFFF );
 455                         // Add to new table
 456                         if(gaPageTable[page] & PF_WRITE) {
 457                                 gaTmpTable[page] = (gaPageTable[page] & ~PF_WRITE) | PF_COW;
 458                                 gaPageTable[page] = (gaPageTable[page] & ~PF_WRITE) | PF_COW;
 459                                 INVLPG( page << 12 );
 460                         }
 461                         else
 462                                 gaTmpTable[page] = gaPageTable[page];
 463                 }
 464         }
 465
 466         // Map in kernel tables (and make fractal mapping)
 467         for( i = 768; i < 1024; i ++ )
 468         {
 469                 // Fractal
 470                 if( i == (PAGE_TABLE_ADDR >> 22) ) {
 471                         gaTmpDir[ PAGE_TABLE_ADDR >> 22 ] = *gTmpCR3;
 472                         continue;
 473                 }
 474
 475                 if( gaPageDir[i] == 0 ) {
 476                         gaTmpDir[i] = 0;
 477                         continue;
 478                 }
 479
 480                 //LOG("gaPageDir[%x/4] = 0x%x", i*4, gaPageDir[i]);
 481                 MM_RefPhys( gaPageDir[i] & ~0xFFF );
 482                 gaTmpDir[i] = gaPageDir[i];
 483         }
 484
 485         // Allocate kernel stack
 486         for(i = KERNEL_STACKS >> 22;
 487                 i < KERNEL_STACK_END >> 22;
 488                 i ++ )
 489         {
 490                 // Check if directory is allocated
 491                 if( (gaPageDir[i] & 1) == 0 ) {
 492                         gaTmpDir[i] = 0;
 493                         continue;
 494                 }
 495
 496                 // We don't care about other kernel stacks, just the current one
 497                 if( i != kStackBase >> 22 ) {
 498                         MM_DerefPhys( gaPageDir[i] & ~0xFFF );
 499                         gaTmpDir[i] = 0;
 500                         continue;
 501                 }
 502
 503                 // Create a copy
 504                 gaTmpDir[i] = MM_AllocPhys() | 3;
 505                 INVLPG( &gaTmpTable[i*1024] );
 506                 for( j = 0; j < 1024; j ++ )
 507                 {
 508                         // Is the page allocated? If not, skip
 509                         if( !(gaPageTable[i*1024+j] & 1) ) {
 510                                 gaTmpTable[i*1024+j] = 0;
 511                                 continue;
 512                         }
 513
 514                         // We don't care about other kernel stacks
 515                         if( ((i*1024+j)*4096 & ~(KERNEL_STACK_SIZE-1)) != kStackBase ) {
 516                                 gaTmpTable[i*1024+j] = 0;
 517                                 continue;
 518                         }
 519
 520                         // Allocate page
 521                         gaTmpTable[i*1024+j] = MM_AllocPhys() | 3;
 522
 523                         MM_RefPhys( gaTmpTable[i*1024+j] & ~0xFFF );
 524
 525                         tmp = (void *) MM_MapTemp( gaTmpTable[i*1024+j] & ~0xFFF );
 526                         memcpy( tmp, (void *)( (i*1024+j)*0x1000 ), 0x1000 );
 527                         MM_FreeTemp( (Uint)tmp );
 528                 }
 529         }
 530
 531         //LEAVE('x', *gTmpCR3 & ~0xFFF);
 532         return *gTmpCR3 & ~0xFFF;
 533 }
 534
 535 /**
 536  * \fn Uint MM_NewKStack()
 537  * \brief Create a new kernel stack
 538  */
 539 Uint MM_NewKStack()
 540 {
 541         Uint    base = KERNEL_STACKS;
 542         Uint    i;
 543         for(;base<KERNEL_STACK_END;base+=KERNEL_STACK_SIZE)
 544         {
 545                 if(MM_GetPhysAddr(base) != 0)   continue;
 546                 for(i=0;i<KERNEL_STACK_SIZE;i+=0x1000) {
 547                         MM_Allocate(base+i);
 548                 }
 549                 return base+KERNEL_STACK_SIZE;
 550         }
 551         Warning("MM_NewKStack - No address space left\n");
 552         return 0;
 553 }
 554
 555 /**
 556  * \fn void MM_SetFlags(Uint VAddr, Uint Flags, Uint Mask)
 557  * \brief Sets the flags on a page
 558  */
 559 void MM_SetFlags(Uint VAddr, Uint Flags, Uint Mask)
 560 {
 561         tPAddr  *ent;
 562         if( !(gaPageDir[VAddr >> 22] & 1) )     return ;
 563         if( !(gaPageTable[VAddr >> 12] & 1) )   return ;
 564
 565         ent = &gaPageTable[VAddr >> 12];
 566
 567         // Read-Only
 568         if( Mask & MM_PFLAG_RO )
 569         {
 570                 if( Flags & MM_PFLAG_RO )       *ent &= ~PF_WRITE;
 571                 else    *ent |= PF_WRITE;
 572         }
 573
 574         // Kernel
 575         if( Mask & MM_PFLAG_KERNEL )
 576         {
 577                 if( Flags & MM_PFLAG_KERNEL )   *ent &= ~PF_USER;
 578                 else    *ent |= PF_USER;
 579         }
 580
 581         // Copy-On-Write
 582         if( Mask & MM_PFLAG_COW )
 583         {
 584                 if( Flags & MM_PFLAG_COW ) {
 585                         *ent &= ~PF_WRITE;
 586                         *ent |= PF_COW;
 587                 }
 588                 else {
 589                         *ent &= ~PF_COW;
 590                         *ent |= PF_WRITE;
 591                 }
 592         }
 593 }
 594
 595 /**
 596  * \fn tPAddr MM_DuplicatePage(Uint VAddr)
 597  * \brief Duplicates a virtual page to a physical one
 598  */
 599 tPAddr MM_DuplicatePage(Uint VAddr)
 600 {
 601         tPAddr  ret;
 602         Uint    temp;
 603          int    wasRO = 0;
 604
 605         // Check if mapped
 606         if( !(gaPageDir  [VAddr >> 22] & PF_PRESENT) )  return 0;
 607         if( !(gaPageTable[VAddr >> 12] & PF_PRESENT) )  return 0;
 608
 609         // Page Align
 610         VAddr &= ~0xFFF;
 611
 612         // Allocate new page
 613         ret = MM_AllocPhys();
 614
 615         // Write-lock the page (to keep data constistent), saving its R/W state
 616         wasRO = (gaPageTable[VAddr >> 12] & PF_WRITE ? 0 : 1);
 617         gaPageTable[VAddr >> 12] &= ~PF_WRITE;
 618         INVLPG( VAddr );
 619
 620         // Copy Data
 621         temp = MM_MapTemp(ret);
 622         memcpy( (void*)temp, (void*)VAddr, 0x1000 );
 623         MM_FreeTemp(temp);
 624
 625         // Restore Writeable status
 626         if(!wasRO)      gaPageTable[VAddr >> 12] |= PF_WRITE;
 627         INVLPG(VAddr);
 628
 629         return ret;
 630 }
 631
 632 /**
 633  * \fn Uint MM_MapTemp(tPAddr PAddr)
 634  * \brief Create a temporary memory mapping
 635  * \todo Show Luigi Barone (C Lecturer) and see what he thinks
 636  */
 637 Uint MM_MapTemp(tPAddr PAddr)
 638 {
 639          int    i;
 640
 641         //ENTER("XPAddr", PAddr);
 642
 643         PAddr &= ~0xFFF;
 644
 645         //LOG("gilTempMappings = %i", gilTempMappings);
 646
 647         for(;;)
 648         {
 649                 LOCK( &gilTempMappings );
 650
 651                 for( i = 0; i < NUM_TEMP_PAGES; i ++ )
 652                 {
 653                         // Check if page used
 654                         if(gaPageTable[ (TEMP_MAP_ADDR >> 12) + i ] & 1)        continue;
 655                         // Mark as used
 656                         gaPageTable[ (TEMP_MAP_ADDR >> 12) + i ] = PAddr | 3;
 657                         INVLPG( TEMP_MAP_ADDR + (i << 12) );
 658                         //LEAVE('p', TEMP_MAP_ADDR + (i << 12));
 659                         RELEASE( &gilTempMappings );
 660                         return TEMP_MAP_ADDR + (i << 12);
 661                 }
 662                 RELEASE( &gilTempMappings );
 663                 Threads_Yield();
 664         }
 665 }
 666
 667 /**
 668  * \fn void MM_FreeTemp(Uint PAddr)
 669  * \brief Free's a temp mapping
 670  */
 671 void MM_FreeTemp(Uint VAddr)
 672 {
 673          int    i = VAddr >> 12;
 674         //ENTER("xVAddr", VAddr);
 675
 676         if(i >= (TEMP_MAP_ADDR >> 12))
 677                 gaPageTable[ i ] = 0;
 678
 679         //LEAVE('-');
 680 }
 681
 682 /**
 683  * \fn Uint MM_MapHWPage(tPAddr PAddr, Uint Number)
 684  * \brief Allocates a contigous number of pages
 685  */
 686 Uint MM_MapHWPage(tPAddr PAddr, Uint Number)
 687 {
 688          int    i, j;
 689
 690         PAddr &= ~0xFFF;
 691
 692         // Scan List
 693         for( i = 0; i < NUM_HW_PAGES; i ++ )
 694         {
 695                 // Check if addr used
 696                 if( gaPageTable[ (HW_MAP_ADDR >> 12) + i ] & 1 )
 697                         continue;
 698
 699                 // Check possible region
 700                 for( j = 0; j < Number && i + j < NUM_HW_PAGES; j ++ )
 701                 {
 702                         // If there is an allocated page in the region we are testing, break
 703                         if( gaPageTable[ (HW_MAP_ADDR >> 12) + i + j ] & 1 )    break;
 704                 }
 705                 // Is it all free?
 706                 if( j == Number )
 707                 {
 708                         // Allocate
 709                         for( j = 0; j < Number; j++ ) {
 710                                 MM_RefPhys( PAddr + (j<<12) );
 711                                 gaPageTable[ (HW_MAP_ADDR >> 12) + i + j ] = (PAddr + (j<<12)) | 3;
 712                         }
 713                         return HW_MAP_ADDR + (i<<12);
 714                 }
 715         }
 716         // If we don't find any, return NULL
 717         return 0;
 718 }
 719
 720 /**
 721  * \fn void MM_UnmapHWPage(Uint VAddr, Uint Number)
 722  * \brief Unmap a hardware page
 723  */
 724 void MM_UnmapHWPage(Uint VAddr, Uint Number)
 725 {
 726          int    i, j;
 727         // Sanity Check
 728         if(VAddr < HW_MAP_ADDR || VAddr-Number*0x1000 > HW_MAP_MAX)     return;
 729
 730         i = VAddr >> 12;
 731
 732         LOCK( &gilTempMappings );       // Temp and HW share a directory, so they share a lock
 733
 734         for( j = 0; j < Number; j++ )
 735         {
 736                 MM_DerefPhys( gaPageTable[ (HW_MAP_ADDR >> 12) + i + j ] );
 737                 gaPageTable[ (HW_MAP_ADDR >> 12) + i + j ] = 0;
 738         }
 739
 740         RELEASE( &gilTempMappings );
 741 }
 742
 743 // --- EXPORTS ---
 744 EXPORT(MM_GetPhysAddr);
 745 EXPORT(MM_Map);
 746 //EXPORT(MM_Unmap);
 747 EXPORT(MM_MapHWPage);
 748 EXPORT(MM_UnmapHWPage);