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