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_STACKS_END       0xFD000000
  20 #define WORKER_STACKS           0x00100000      // Thread0 Only!
  21 #define WORKER_STACK_SIZE       KERNEL_STACK_SIZE
  22 #define WORKER_STACKS_END       0xB0000000
  23 #define NUM_WORKER_STACKS       ((WORKER_STACKS_END-WORKER_STACKS)/WORKER_STACK_SIZE)
  24 #define PAGE_TABLE_ADDR 0xFD000000
  25 #define PAGE_DIR_ADDR   0xFD3F4000
  26 #define PAGE_CR3_ADDR   0xFD3F4FD0
  27 #define TMP_CR3_ADDR    0xFD3F4FD4      // Part of core instead of temp
  28 #define TMP_DIR_ADDR    0xFD3F5000      // Same
  29 #define TMP_TABLE_ADDR  0xFD400000
  30 #define HW_MAP_ADDR             0xFD800000
  31 #define HW_MAP_MAX              0xFEFF0000
  32 #define NUM_HW_PAGES    ((HW_MAP_MAX-HW_MAP_ADDR)/0x1000)
  33 #define TEMP_MAP_ADDR   0xFEFF0000      // Allows 16 "temp" pages
  34 #define NUM_TEMP_PAGES  16
  35
  36 #define PF_PRESENT      0x1
  37 #define PF_WRITE        0x2
  38 #define PF_USER         0x4
  39 #define PF_COW          0x200
  40 #define PF_PAGED        0x400
  41
  42 #define INVLPG(addr)    __asm__ __volatile__ ("invlpg (%0)"::"r"(addr))
  43
  44 // === IMPORTS ===
  45 extern Uint32   gaInitPageDir[1024];
  46 extern Uint32   gaInitPageTable[1024];
  47 extern void     Threads_SegFault(tVAddr Addr);
  48 extern void     Error_Backtrace(Uint eip, Uint ebp);
  49
  50 // === PROTOTYPES ===
  51 void    MM_PreinitVirtual();
  52 void    MM_InstallVirtual();
  53 void    MM_PageFault(tVAddr Addr, Uint ErrorCode, tRegs *Regs);
  54 void    MM_DumpTables(tVAddr Start, tVAddr End);
  55 tPAddr  MM_DuplicatePage(tVAddr VAddr);
  56
  57 // === GLOBALS ===
  58 tPAddr  *gaPageTable = (void*)PAGE_TABLE_ADDR;
  59 tPAddr  *gaPageDir = (void*)PAGE_DIR_ADDR;
  60 tPAddr  *gaPageCR3 = (void*)PAGE_CR3_ADDR;
  61 tPAddr  *gaTmpTable = (void*)TMP_TABLE_ADDR;
  62 tPAddr  *gaTmpDir = (void*)TMP_DIR_ADDR;
  63 tPAddr  *gTmpCR3 = (void*)TMP_CR3_ADDR;
  64  int    gilTempMappings = 0;
  65  int    gilTempFractal = 0;
  66 Uint32  gWorkerStacks[NUM_WORKER_STACKS/32];
  67  int    giLastUsedWorker = 0;
  68
  69 // === CODE ===
  70 /**
  71  * \fn void MM_PreinitVirtual()
  72  * \brief Maps the fractal mappings
  73  */
  74 void MM_PreinitVirtual()
  75 {
  76         gaInitPageDir[ 0 ] = 0;
  77         gaInitPageDir[ PAGE_TABLE_ADDR >> 22 ] = ((Uint)&gaInitPageDir - KERNEL_BASE) | 3;
  78 }
  79
  80 /**
  81  * \fn void MM_InstallVirtual()
  82  * \brief Sets up the constant page mappings
  83  */
  84 void MM_InstallVirtual()
  85 {
  86          int    i;
  87
  88         // --- Pre-Allocate kernel tables
  89         for( i = KERNEL_BASE>>22; i < 1024; i ++ )
  90         {
  91                 if( gaPageDir[ i ] )    continue;
  92                 // Skip stack tables, they are process unique
  93                 if( i > KERNEL_STACKS >> 22 && i < KERNEL_STACKS_END >> 22) {
  94                         gaPageDir[ i ] = 0;
  95                         continue;
  96                 }
  97                 // Preallocate table
  98                 gaPageDir[ i ] = MM_AllocPhys() | 3;
  99                 INVLPG( &gaPageTable[i*1024] );
 100                 memset( &gaPageTable[i*1024], 0, 0x1000 );
 101         }
 102 }
 103
 104 /**
 105  * \fn void MM_PageFault(tVAddr Addr, Uint ErrorCode, tRegs *Regs)
 106  * \brief Called on a page fault
 107  */
 108 void MM_PageFault(tVAddr Addr, Uint ErrorCode, tRegs *Regs)
 109 {
 110         //ENTER("xAddr bErrorCode", Addr, ErrorCode);
 111
 112         // -- Check for COW --
 113         if( gaPageDir  [Addr>>22] & PF_PRESENT
 114          && gaPageTable[Addr>>12] & PF_PRESENT
 115          && gaPageTable[Addr>>12] & PF_COW )
 116         {
 117                 tPAddr  paddr;
 118                 if(MM_GetRefCount( gaPageTable[Addr>>12] & ~0xFFF ) == 1)
 119                 {
 120                         gaPageTable[Addr>>12] &= ~PF_COW;
 121                         gaPageTable[Addr>>12] |= PF_PRESENT|PF_WRITE;
 122                 }
 123                 else
 124                 {
 125                         paddr = MM_DuplicatePage( Addr );
 126                         MM_DerefPhys( gaPageTable[Addr>>12] & ~0xFFF );
 127                         gaPageTable[Addr>>12] &= PF_USER;
 128                         gaPageTable[Addr>>12] |= paddr|PF_PRESENT|PF_WRITE;
 129                 }
 130
 131                 INVLPG( Addr & ~0xFFF );
 132                 //LEAVE('-')
 133                 return;
 134         }
 135
 136         // If it was a user, tell the thread handler
 137         if(ErrorCode & 4) {
 138                 Warning("%s %s %s memory%s",
 139                         (ErrorCode&4?"User":"Kernel"),
 140                         (ErrorCode&2?"write to":"read from"),
 141                         (ErrorCode&1?"bad/locked":"non-present"),
 142                         (ErrorCode&16?" (Instruction Fetch)":"")
 143                         );
 144                 Warning("User Pagefault: Instruction at %p accessed %p", Regs->eip, Addr);
 145                 __asm__ __volatile__ ("sti");   // Restart IRQs
 146                 Threads_SegFault(Addr);
 147                 return ;
 148         }
 149
 150         // -- Check Error Code --
 151         if(ErrorCode & 8)
 152                 Warning("Reserved Bits Trashed!");
 153         else
 154         {
 155                 Warning("%s %s %s memory%s",
 156                         (ErrorCode&4?"User":"Kernel"),
 157                         (ErrorCode&2?"write to":"read from"),
 158                         (ErrorCode&1?"bad/locked":"non-present"),
 159                         (ErrorCode&16?" (Instruction Fetch)":"")
 160                         );
 161         }
 162
 163         Log("Code at %p accessed %p", Regs->eip, Addr);
 164         // Print Stack Backtrace
 165         Error_Backtrace(Regs->eip, Regs->ebp);
 166
 167         Log("gaPageDir[0x%x] = 0x%x", Addr>>22, gaPageDir[Addr>>22]);
 168         if( gaPageDir[Addr>>22] & PF_PRESENT )
 169                 Log("gaPageTable[0x%x] = 0x%x", Addr>>12, gaPageTable[Addr>>12]);
 170
 171         MM_DumpTables(0, -1);
 172
 173         Panic("Page Fault at 0x%x\n", Regs->eip);
 174 }
 175
 176 /**
 177  * \fn void MM_DumpTables(tVAddr Start, tVAddr End)
 178  * \brief Dumps the layout of the page tables
 179  */
 180 void MM_DumpTables(tVAddr Start, tVAddr End)
 181 {
 182         tVAddr  rangeStart = 0;
 183         tPAddr  expected = 0;
 184         tVAddr  curPos;
 185         Uint    page;
 186         const tPAddr    MASK = ~0xF98;
 187
 188         Start >>= 12;   End >>= 12;
 189
 190         #if 0
 191         Log("Directory Entries:");
 192         for(page = Start >> 10;
 193                 page < (End >> 10)+1;
 194                 page ++)
 195         {
 196                 if(gaPageDir[page])
 197                 {
 198                         Log(" 0x%08x-0x%08x :: 0x%08x",
 199                                 page<<22, ((page+1)<<22)-1,
 200                                 gaPageDir[page]&~0xFFF
 201                                 );
 202                 }
 203         }
 204         #endif
 205
 206         Log("Table Entries:");
 207         for(page = Start, curPos = Start<<12;
 208                 page < End;
 209                 curPos += 0x1000, page++)
 210         {
 211                 if( !(gaPageDir[curPos>>22] & PF_PRESENT)
 212                 ||  !(gaPageTable[page] & PF_PRESENT)
 213                 ||  (gaPageTable[page] & MASK) != expected)
 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                         if( !(gaPageDir[curPos>>22] & PF_PRESENT) )     continue;
 228                         if( !(gaPageTable[curPos>>12] & PF_PRESENT) )   continue;
 229
 230                         expected = (gaPageTable[page] & MASK);
 231                         rangeStart = curPos;
 232                 }
 233                 if(expected)    expected += 0x1000;
 234         }
 235
 236         if(expected) {
 237                 Log("0x%08x-0x%08x => 0x%08x-0x%08x (%s%s%s%s)",
 238                         rangeStart, curPos - 1,
 239                         gaPageTable[rangeStart>>12] & ~0xFFF,
 240                         (expected & ~0xFFF) - 1,
 241                         (expected & PF_PAGED ? "p" : "-"),
 242                         (expected & PF_COW ? "C" : "-"),
 243                         (expected & PF_USER ? "U" : "-"),
 244                         (expected & PF_WRITE ? "W" : "-")
 245                         );
 246                 expected = 0;
 247         }
 248 }
 249
 250 /**
 251  * \fn tPAddr MM_Allocate(tVAddr VAddr)
 252  */
 253 tPAddr MM_Allocate(tVAddr VAddr)
 254 {
 255         tPAddr  paddr;
 256         // Check if the directory is mapped
 257         if( gaPageDir[ VAddr >> 22 ] == 0 )
 258         {
 259                 // Allocate directory
 260                 paddr = MM_AllocPhys();
 261                 if( paddr == 0 ) {
 262                         Warning("MM_Allocate - Out of Memory (Called by %p)", __builtin_return_address(0));
 263                         return 0;
 264                 }
 265                 // Map
 266                 gaPageDir[ VAddr >> 22 ] = paddr | 3;
 267                 // Mark as user
 268                 if(VAddr < MM_USER_MAX) gaPageDir[ VAddr >> 22 ] |= PF_USER;
 269
 270                 INVLPG( &gaPageDir[ VAddr >> 22 ] );
 271                 memsetd( &gaPageTable[ (VAddr >> 12) & ~0x3FF ], 0, 1024 );
 272         }
 273         // Check if the page is already allocated
 274         else if( gaPageTable[ VAddr >> 12 ] != 0 ) {
 275                 Warning("MM_Allocate - Allocating to used address (%p)", VAddr);
 276                 return gaPageTable[ VAddr >> 12 ] & ~0xFFF;
 277         }
 278
 279         // Allocate
 280         paddr = MM_AllocPhys();
 281         if( paddr == 0 ) {
 282                 Warning("MM_Allocate - Out of Memory when allocating at %p (Called by %p)",
 283                         VAddr, __builtin_return_address(0));
 284                 return 0;
 285         }
 286         // Map
 287         gaPageTable[ VAddr >> 12 ] = paddr | 3;
 288         // Mark as user
 289         if(VAddr < MM_USER_MAX) gaPageTable[ VAddr >> 12 ] |= PF_USER;
 290         // Invalidate Cache for address
 291         INVLPG( VAddr & ~0xFFF );
 292
 293         return paddr;
 294 }
 295
 296 /**
 297  * \fn void MM_Deallocate(tVAddr VAddr)
 298  */
 299 void MM_Deallocate(tVAddr VAddr)
 300 {
 301         if( gaPageDir[ VAddr >> 22 ] == 0 ) {
 302                 Warning("MM_Deallocate - Directory not mapped");
 303                 return;
 304         }
 305
 306         if(gaPageTable[ VAddr >> 12 ] == 0) {
 307                 Warning("MM_Deallocate - Page is not allocated");
 308                 return;
 309         }
 310
 311         // Dereference page
 312         MM_DerefPhys( gaPageTable[ VAddr >> 12 ] & ~0xFFF );
 313         // Clear page
 314         gaPageTable[ VAddr >> 12 ] = 0;
 315 }
 316
 317 /**
 318  * \fn tPAddr MM_GetPhysAddr(tVAddr Addr)
 319  * \brief Checks if the passed address is accesable
 320  */
 321 tPAddr MM_GetPhysAddr(tVAddr Addr)
 322 {
 323         if( !(gaPageDir[Addr >> 22] & 1) )
 324                 return 0;
 325         if( !(gaPageTable[Addr >> 12] & 1) )
 326                 return 0;
 327         return (gaPageTable[Addr >> 12] & ~0xFFF) | (Addr & 0xFFF);
 328 }
 329
 330
 331 /**
 332  * \fn int MM_IsUser(tVAddr Addr)
 333  * \brief Checks if a page is user accessable
 334  */
 335 int MM_IsUser(tVAddr Addr)
 336 {
 337         if( !(gaPageDir[Addr >> 22] & 1) )
 338                 return 0;
 339         if( !(gaPageTable[Addr >> 12] & 1) )
 340                 return 0;
 341         if( !(gaPageTable[Addr >> 12] & PF_USER) )
 342                 return 0;
 343         return 1;
 344 }
 345
 346 /**
 347  * \fn void MM_SetCR3(tPAddr CR3)
 348  * \brief Sets the current process space
 349  */
 350 void MM_SetCR3(tPAddr CR3)
 351 {
 352         __asm__ __volatile__ ("mov %0, %%cr3"::"r"(CR3));
 353 }
 354
 355 /**
 356  * \fn int MM_Map(tVAddr VAddr, tPAddr PAddr)
 357  * \brief Map a physical page to a virtual one
 358  */
 359 int MM_Map(tVAddr VAddr, tPAddr PAddr)
 360 {
 361         //ENTER("xVAddr xPAddr", VAddr, PAddr);
 362         // Sanity check
 363         if( PAddr & 0xFFF || VAddr & 0xFFF ) {
 364                 Warning("MM_Map - Physical or Virtual Addresses are not aligned");
 365                 //LEAVE('i', 0);
 366                 return 0;
 367         }
 368
 369         // Align addresses
 370         PAddr &= ~0xFFF;        VAddr &= ~0xFFF;
 371
 372         // Check if the directory is mapped
 373         if( gaPageDir[ VAddr >> 22 ] == 0 )
 374         {
 375                 gaPageDir[ VAddr >> 22 ] = MM_AllocPhys() | 3;
 376
 377                 // Mark as user
 378                 if(VAddr < MM_USER_MAX) gaPageDir[ VAddr >> 22 ] |= PF_USER;
 379
 380                 INVLPG( &gaPageTable[ (VAddr >> 12) & ~0x3FF ] );
 381                 memsetd( &gaPageTable[ (VAddr >> 12) & ~0x3FF ], 0, 1024 );
 382         }
 383         // Check if the page is already allocated
 384         else if( gaPageTable[ VAddr >> 12 ] != 0 ) {
 385                 Warning("MM_Map - Allocating to used address");
 386                 //LEAVE('i', 0);
 387                 return 0;
 388         }
 389
 390         // Map
 391         gaPageTable[ VAddr >> 12 ] = PAddr | 3;
 392         // Mark as user
 393         if(VAddr < MM_USER_MAX) gaPageTable[ VAddr >> 12 ] |= PF_USER;
 394
 395         //LOG("gaPageTable[ 0x%x ] = (Uint)%p = 0x%x",
 396         //      VAddr >> 12, &gaPageTable[ VAddr >> 12 ], gaPageTable[ VAddr >> 12 ]);
 397
 398         // Reference
 399         MM_RefPhys( PAddr );
 400
 401         //LOG("INVLPG( 0x%x )", VAddr);
 402         INVLPG( VAddr );
 403
 404         //LEAVE('i', 1);
 405         return 1;
 406 }
 407
 408 /**
 409  * \fn tVAddr MM_ClearUser()
 410  * \brief Clear user's address space
 411  */
 412 tVAddr MM_ClearUser()
 413 {
 414         Uint    i, j;
 415
 416         // Copy Directories
 417         for( i = 0; i < (MM_USER_MAX>>22); i ++ )
 418         {
 419                 // Check if directory is not allocated
 420                 if( !(gaPageDir[i] & PF_PRESENT) ) {
 421                         gaPageDir[i] = 0;
 422                         continue;
 423                 }
 424
 425
 426                 for( j = 0; j < 1024; j ++ )
 427                 {
 428                         if( gaPageTable[i*1024+j] & 1 )
 429                                 MM_DerefPhys( gaPageTable[i*1024+j] & ~0xFFF );
 430                         gaPageTable[i*1024+j] = 0;
 431                 }
 432
 433                 MM_DerefPhys( gaPageDir[i] & ~0xFFF );
 434                 gaPageDir[i] = 0;
 435                 INVLPG( &gaPageTable[i*1024] );
 436         }
 437         INVLPG( gaPageDir );
 438
 439         return *gaPageCR3;
 440 }
 441
 442 /**
 443  * \fn tPAddr MM_Clone()
 444  * \brief Clone the current address space
 445  */
 446 tPAddr MM_Clone()
 447 {
 448         Uint    i, j;
 449         tVAddr  ret;
 450         Uint    page = 0;
 451         tVAddr  kStackBase = Proc_GetCurThread()->KernelStack - KERNEL_STACK_SIZE;
 452         void    *tmp;
 453
 454         LOCK( &gilTempFractal );
 455
 456         // Create Directory Table
 457         *gTmpCR3 = MM_AllocPhys() | 3;
 458         INVLPG( gaTmpDir );
 459         //LOG("Allocated Directory (%x)", *gTmpCR3);
 460         memsetd( gaTmpDir, 0, 1024 );
 461
 462         // Copy Tables
 463         for(i=0;i<768;i++)
 464         {
 465                 // Check if table is allocated
 466                 if( !(gaPageDir[i] & PF_PRESENT) ) {
 467                         gaTmpDir[i] = 0;
 468                         page += 1024;
 469                         continue;
 470                 }
 471
 472                 // Allocate new table
 473                 gaTmpDir[i] = MM_AllocPhys() | (gaPageDir[i] & 7);
 474                 INVLPG( &gaTmpTable[page] );
 475                 // Fill
 476                 for( j = 0; j < 1024; j ++, page++ )
 477                 {
 478                         if( !(gaPageTable[page] & PF_PRESENT) ) {
 479                                 gaTmpTable[page] = 0;
 480                                 continue;
 481                         }
 482
 483                         // Refrence old page
 484                         MM_RefPhys( gaPageTable[page] & ~0xFFF );
 485                         // Add to new table
 486                         if(gaPageTable[page] & PF_WRITE) {
 487                                 gaTmpTable[page] = (gaPageTable[page] & ~PF_WRITE) | PF_COW;
 488                                 gaPageTable[page] = (gaPageTable[page] & ~PF_WRITE) | PF_COW;
 489                                 INVLPG( page << 12 );
 490                         }
 491                         else
 492                                 gaTmpTable[page] = gaPageTable[page];
 493                 }
 494         }
 495
 496         // Map in kernel tables (and make fractal mapping)
 497         for( i = 768; i < 1024; i ++ )
 498         {
 499                 // Fractal
 500                 if( i == (PAGE_TABLE_ADDR >> 22) ) {
 501                         gaTmpDir[ PAGE_TABLE_ADDR >> 22 ] = *gTmpCR3;
 502                         continue;
 503                 }
 504
 505                 if( gaPageDir[i] == 0 ) {
 506                         gaTmpDir[i] = 0;
 507                         continue;
 508                 }
 509
 510                 //LOG("gaPageDir[%x/4] = 0x%x", i*4, gaPageDir[i]);
 511                 MM_RefPhys( gaPageDir[i] & ~0xFFF );
 512                 gaTmpDir[i] = gaPageDir[i];
 513         }
 514
 515         // Allocate kernel stack
 516         for(i = KERNEL_STACKS >> 22;
 517                 i < KERNEL_STACKS_END >> 22;
 518                 i ++ )
 519         {
 520                 // Check if directory is allocated
 521                 if( (gaPageDir[i] & 1) == 0 ) {
 522                         gaTmpDir[i] = 0;
 523                         continue;
 524                 }
 525
 526                 // We don't care about other kernel stacks, just the current one
 527                 if( i != kStackBase >> 22 ) {
 528                         MM_DerefPhys( gaPageDir[i] & ~0xFFF );
 529                         gaTmpDir[i] = 0;
 530                         continue;
 531                 }
 532
 533                 // Create a copy
 534                 gaTmpDir[i] = MM_AllocPhys() | 3;
 535                 INVLPG( &gaTmpTable[i*1024] );
 536                 for( j = 0; j < 1024; j ++ )
 537                 {
 538                         // Is the page allocated? If not, skip
 539                         if( !(gaPageTable[i*1024+j] & 1) ) {
 540                                 gaTmpTable[i*1024+j] = 0;
 541                                 continue;
 542                         }
 543
 544                         // We don't care about other kernel stacks
 545                         if( ((i*1024+j)*4096 & ~(KERNEL_STACK_SIZE-1)) != kStackBase ) {
 546                                 gaTmpTable[i*1024+j] = 0;
 547                                 continue;
 548                         }
 549
 550                         // Allocate page
 551                         gaTmpTable[i*1024+j] = MM_AllocPhys() | 3;
 552
 553                         MM_RefPhys( gaTmpTable[i*1024+j] & ~0xFFF );
 554
 555                         tmp = (void *) MM_MapTemp( gaTmpTable[i*1024+j] & ~0xFFF );
 556                         memcpy( tmp, (void *)( (i*1024+j)*0x1000 ), 0x1000 );
 557                         MM_FreeTemp( (Uint)tmp );
 558                 }
 559         }
 560
 561         ret = *gTmpCR3 & ~0xFFF;
 562         RELEASE( &gilTempFractal );
 563
 564         //LEAVE('x', ret);
 565         return ret;
 566 }
 567
 568 /**
 569  * \fn tVAddr MM_NewKStack()
 570  * \brief Create a new kernel stack
 571  */
 572 tVAddr MM_NewKStack()
 573 {
 574         tVAddr  base = KERNEL_STACKS;
 575         Uint    i;
 576         for(;base<KERNEL_STACKS_END;base+=KERNEL_STACK_SIZE)
 577         {
 578                 if(MM_GetPhysAddr(base) != 0)   continue;
 579                 for(i=0;i<KERNEL_STACK_SIZE;i+=0x1000) {
 580                         MM_Allocate(base+i);
 581                 }
 582                 return base+KERNEL_STACK_SIZE;
 583         }
 584         Warning("MM_NewKStack - No address space left\n");
 585         return 0;
 586 }
 587
 588 /**
 589  * \fn tVAddr MM_NewWorkerStack()
 590  * \brief Creates a new worker stack
 591  */
 592 tVAddr MM_NewWorkerStack()
 593 {
 594         Uint    esp, ebp;
 595         Uint    oldstack;
 596         Uint    base, addr;
 597          int    i, j;
 598         Uint    *tmpPage;
 599         tPAddr  pages[WORKER_STACK_SIZE>>12];
 600
 601         // Get the old ESP and EBP
 602         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 603         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 604
 605         // Find a free worker stack address
 606         for(base = giLastUsedWorker; base < NUM_WORKER_STACKS; base++)
 607         {
 608                 // Used block
 609                 if( gWorkerStacks[base/32] == -1 ) {
 610                         base += 31;     base &= ~31;
 611                         base --;        // Counteracted by the base++
 612                         continue;
 613                 }
 614                 // Used stack
 615                 if( gWorkerStacks[base/32] & (1 << base) ) {
 616                         continue;
 617                 }
 618         }
 619         if(base >= NUM_WORKER_STACKS) {
 620                 Warning("Uh-oh! Out of worker stacks");
 621                 return 0;
 622         }
 623
 624         // It's ours now!
 625         gWorkerStacks[base/32] |= (1 << base);
 626         // Make life easier for later calls
 627         giLastUsedWorker = base;
 628         // We have one
 629         base = WORKER_STACKS + base * WORKER_STACK_SIZE;
 630
 631         // Acquire the lock for the temp fractal mappings
 632         LOCK(&gilTempFractal);
 633
 634         // Set the temp fractals to TID0's address space
 635         *gTmpCR3 = (Uint)gaInitPageDir | 3;
 636         INVLPG( gaTmpDir );
 637
 638         // Check if the directory is mapped (we are assuming that the stacks
 639         // will fit neatly in a directory
 640         if(gaTmpDir[ base >> 22 ] == 0) {
 641                 gaTmpDir[ base >> 22 ] = MM_AllocPhys() | 3;
 642                 INVLPG( &gaTmpTable[ (base>>22) & ~0x3FF ] );
 643         }
 644
 645         // Mapping Time!
 646         for( addr = 0; addr < WORKER_STACK_SIZE; addr += 0x1000 )
 647         {
 648                 pages[ addr >> 12 ] = MM_AllocPhys();
 649                 gaTmpTable[ (base + addr) >> 12 ] = pages[addr>>12] | 3;
 650         }
 651         // Release the temp mapping lock
 652         RELEASE(&gilTempFractal);
 653
 654         // Copy the old stack
 655         oldstack = (esp + KERNEL_STACK_SIZE-1) & ~(KERNEL_STACK_SIZE-1);
 656         esp = oldstack - esp;   // ESP as an offset in the stack
 657
 658         i = (WORKER_STACK_SIZE>>12) - 1;
 659         // Copy the contents of the old stack to the new one, altering the addresses
 660         // `addr` is refering to bytes from the stack base (mem downwards)
 661         for(addr = 0; addr < esp; addr += 0x1000)
 662         {
 663                 Uint    *stack = (Uint*)( oldstack-(addr+0x1000) );
 664                 tmpPage = (void*)MM_MapTemp( pages[i] );
 665                 // Copy old stack
 666                 for(j = 0; j < 1024; j++)
 667                 {
 668                         // Possible Stack address?
 669                         if(oldstack-esp < stack[j] && stack[j] < oldstack)
 670                                 tmpPage[j] = base - (oldstack - stack[j]);
 671                         else    // Seems not, best leave it alone
 672                                 tmpPage[j] = stack[j];
 673                 }
 674                 MM_FreeTemp((Uint)tmpPage);
 675                 i --;
 676         }
 677
 678         return base;
 679 }
 680
 681 /**
 682  * \fn void MM_SetFlags(tVAddr VAddr, Uint Flags, Uint Mask)
 683  * \brief Sets the flags on a page
 684  */
 685 void MM_SetFlags(tVAddr VAddr, Uint Flags, Uint Mask)
 686 {
 687         tPAddr  *ent;
 688         if( !(gaPageDir[VAddr >> 22] & 1) )     return ;
 689         if( !(gaPageTable[VAddr >> 12] & 1) )   return ;
 690
 691         ent = &gaPageTable[VAddr >> 12];
 692
 693         // Read-Only
 694         if( Mask & MM_PFLAG_RO )
 695         {
 696                 if( Flags & MM_PFLAG_RO )       *ent &= ~PF_WRITE;
 697                 else    *ent |= PF_WRITE;
 698         }
 699
 700         // Kernel
 701         if( Mask & MM_PFLAG_KERNEL )
 702         {
 703                 if( Flags & MM_PFLAG_KERNEL )   *ent &= ~PF_USER;
 704                 else    *ent |= PF_USER;
 705         }
 706
 707         // Copy-On-Write
 708         if( Mask & MM_PFLAG_COW )
 709         {
 710                 if( Flags & MM_PFLAG_COW ) {
 711                         *ent &= ~PF_WRITE;
 712                         *ent |= PF_COW;
 713                 }
 714                 else {
 715                         *ent &= ~PF_COW;
 716                         *ent |= PF_WRITE;
 717                 }
 718         }
 719 }
 720
 721 /**
 722  * \fn tPAddr MM_DuplicatePage(tVAddr VAddr)
 723  * \brief Duplicates a virtual page to a physical one
 724  */
 725 tPAddr MM_DuplicatePage(tVAddr VAddr)
 726 {
 727         tPAddr  ret;
 728         Uint    temp;
 729          int    wasRO = 0;
 730
 731         // Check if mapped
 732         if( !(gaPageDir  [VAddr >> 22] & PF_PRESENT) )  return 0;
 733         if( !(gaPageTable[VAddr >> 12] & PF_PRESENT) )  return 0;
 734
 735         // Page Align
 736         VAddr &= ~0xFFF;
 737
 738         // Allocate new page
 739         ret = MM_AllocPhys();
 740
 741         // Write-lock the page (to keep data constistent), saving its R/W state
 742         wasRO = (gaPageTable[VAddr >> 12] & PF_WRITE ? 0 : 1);
 743         gaPageTable[VAddr >> 12] &= ~PF_WRITE;
 744         INVLPG( VAddr );
 745
 746         // Copy Data
 747         temp = MM_MapTemp(ret);
 748         memcpy( (void*)temp, (void*)VAddr, 0x1000 );
 749         MM_FreeTemp(temp);
 750
 751         // Restore Writeable status
 752         if(!wasRO)      gaPageTable[VAddr >> 12] |= PF_WRITE;
 753         INVLPG(VAddr);
 754
 755         return ret;
 756 }
 757
 758 /**
 759  * \fn Uint MM_MapTemp(tPAddr PAddr)
 760  * \brief Create a temporary memory mapping
 761  * \todo Show Luigi Barone (C Lecturer) and see what he thinks
 762  */
 763 tVAddr MM_MapTemp(tPAddr PAddr)
 764 {
 765          int    i;
 766
 767         //ENTER("XPAddr", PAddr);
 768
 769         PAddr &= ~0xFFF;
 770
 771         //LOG("gilTempMappings = %i", gilTempMappings);
 772
 773         for(;;)
 774         {
 775                 LOCK( &gilTempMappings );
 776
 777                 for( i = 0; i < NUM_TEMP_PAGES; i ++ )
 778                 {
 779                         // Check if page used
 780                         if(gaPageTable[ (TEMP_MAP_ADDR >> 12) + i ] & 1)        continue;
 781                         // Mark as used
 782                         gaPageTable[ (TEMP_MAP_ADDR >> 12) + i ] = PAddr | 3;
 783                         INVLPG( TEMP_MAP_ADDR + (i << 12) );
 784                         //LEAVE('p', TEMP_MAP_ADDR + (i << 12));
 785                         RELEASE( &gilTempMappings );
 786                         return TEMP_MAP_ADDR + (i << 12);
 787                 }
 788                 RELEASE( &gilTempMappings );
 789                 Threads_Yield();
 790         }
 791 }
 792
 793 /**
 794  * \fn void MM_FreeTemp(tVAddr PAddr)
 795  * \brief Free's a temp mapping
 796  */
 797 void MM_FreeTemp(tVAddr VAddr)
 798 {
 799          int    i = VAddr >> 12;
 800         //ENTER("xVAddr", VAddr);
 801
 802         if(i >= (TEMP_MAP_ADDR >> 12))
 803                 gaPageTable[ i ] = 0;
 804
 805         //LEAVE('-');
 806 }
 807
 808 /**
 809  * \fn tVAddr MM_MapHWPage(tPAddr PAddr, Uint Number)
 810  * \brief Allocates a contigous number of pages
 811  */
 812 tVAddr MM_MapHWPage(tPAddr PAddr, Uint Number)
 813 {
 814          int    i, j;
 815
 816         PAddr &= ~0xFFF;
 817
 818         // Scan List
 819         for( i = 0; i < NUM_HW_PAGES; i ++ )
 820         {
 821                 // Check if addr used
 822                 if( gaPageTable[ (HW_MAP_ADDR >> 12) + i ] & 1 )
 823                         continue;
 824
 825                 // Check possible region
 826                 for( j = 0; j < Number && i + j < NUM_HW_PAGES; j ++ )
 827                 {
 828                         // If there is an allocated page in the region we are testing, break
 829                         if( gaPageTable[ (HW_MAP_ADDR >> 12) + i + j ] & 1 )    break;
 830                 }
 831                 // Is it all free?
 832                 if( j == Number )
 833                 {
 834                         // Allocate
 835                         for( j = 0; j < Number; j++ ) {
 836                                 MM_RefPhys( PAddr + (j<<12) );
 837                                 gaPageTable[ (HW_MAP_ADDR >> 12) + i + j ] = (PAddr + (j<<12)) | 3;
 838                         }
 839                         return HW_MAP_ADDR + (i<<12);
 840                 }
 841         }
 842         // If we don't find any, return NULL
 843         return 0;
 844 }
 845
 846 /**
 847  * \fn tVAddr MM_AllocDMA(int Pages, int MaxBits, tPAddr *PhysAddr)
 848  * \brief Allocates DMA physical memory
 849  * \param Pages Number of pages required
 850  * \param MaxBits       Maximum number of bits the physical address can have
 851  * \param PhysAddr      Pointer to the location to place the physical address allocated
 852  * \return Virtual address allocate
 853  */
 854 tVAddr MM_AllocDMA(int Pages, int MaxBits, tPAddr *PhysAddr)
 855 {
 856         tPAddr  maxCheck = (1 << MaxBits);
 857         tPAddr  phys;
 858         tVAddr  ret;
 859
 860         ENTER("iPages iMaxBits pPhysAddr", Pages, MaxBits, PhysAddr);
 861
 862         // Sanity Check
 863         if(MaxBits < 12 || !PhysAddr) {
 864                 LEAVE('i', 0);
 865                 return 0;
 866         }
 867
 868         // Bound
 869         if(MaxBits >= PHYS_BITS)        maxCheck = -1;
 870
 871         // Fast Allocate
 872         if(Pages == 1 && MaxBits >= PHYS_BITS)
 873         {
 874                 phys = MM_AllocPhys();
 875                 *PhysAddr = phys;
 876                 ret = MM_MapHWPage(phys, 1);
 877                 if(ret == 0) {
 878                         MM_DerefPhys(phys);
 879                         LEAVE('i', 0);
 880                         return 0;
 881                 }
 882                 LEAVE('x', ret);
 883                 return ret;
 884         }
 885
 886         // Slow Allocate
 887         phys = MM_AllocPhysRange(Pages);
 888         // - Was it allocated?
 889         if(phys == 0) {
 890                 LEAVE('i', 0);
 891                 return 0;
 892         }
 893         // - Check if the memory is OK
 894         if(phys + (Pages-1)*0x1000 > maxCheck)
 895         {
 896                 // Deallocate and return 0
 897                 for(;Pages--;phys+=0x1000)
 898                         MM_DerefPhys(phys);
 899                 LEAVE('i', 0);
 900                 return 0;
 901         }
 902
 903         // Allocated successfully, now map
 904         ret = MM_MapHWPage(phys, Pages);
 905         if( ret == 0 ) {
 906                 // If it didn't map, free then return 0
 907                 for(;Pages--;phys+=0x1000)
 908                         MM_DerefPhys(phys);
 909                 LEAVE('i', 0);
 910                 return 0;
 911         }
 912
 913         *PhysAddr = phys;
 914         LEAVE('x', ret);
 915         return ret;
 916 }
 917
 918 /**
 919  * \fn void MM_UnmapHWPage(tVAddr VAddr, Uint Number)
 920  * \brief Unmap a hardware page
 921  */
 922 void MM_UnmapHWPage(tVAddr VAddr, Uint Number)
 923 {
 924          int    i, j;
 925         // Sanity Check
 926         if(VAddr < HW_MAP_ADDR || VAddr-Number*0x1000 > HW_MAP_MAX)     return;
 927
 928         i = VAddr >> 12;
 929
 930         LOCK( &gilTempMappings );       // Temp and HW share a directory, so they share a lock
 931
 932         for( j = 0; j < Number; j++ )
 933         {
 934                 MM_DerefPhys( gaPageTable[ (HW_MAP_ADDR >> 12) + i + j ] );
 935                 gaPageTable[ (HW_MAP_ADDR >> 12) + i + j ] = 0;
 936         }
 937
 938         RELEASE( &gilTempMappings );
 939 }
 940
 941 // --- EXPORTS ---
 942 EXPORT(MM_GetPhysAddr);
 943 EXPORT(MM_Map);
 944 //EXPORT(MM_Unmap);
 945 EXPORT(MM_MapHWPage);
 946 EXPORT(MM_AllocDMA);
 947 EXPORT(MM_UnmapHWPage);