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