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