Kernel/arch/x86/proc.c

   1 /*
   2  * AcessOS Microkernel Version
   3  * proc.c
   4  */
   5 #include <acess.h>
   6 #include <proc.h>
   7 #include <mm_virt.h>
   8 #include <errno.h>
   9 #if USE_MP
  10 # include <mp.h>
  11 #endif
  12
  13 // === FLAGS ===
  14 #define DEBUG_TRACE_SWITCH      0
  15
  16 // === CONSTANTS ===
  17 #define SWITCH_MAGIC    0xFFFACE55      // There is no code in this area
  18 #define TIMER_DIVISOR   11931   //~100Hz
  19
  20 // === IMPORTS ===
  21 extern tGDT     gGDT[];
  22 extern void APStartup();        // 16-bit AP startup code
  23 extern Uint     GetEIP();       // start.asm
  24 extern Uint32   gaInitPageDir[1024];    // start.asm
  25 extern void     Kernel_Stack_Top;
  26 extern volatile int     giThreadListLock;
  27 extern int      giNumCPUs;
  28 extern int      giNextTID;
  29 extern int      giTotalTickets;
  30 extern int      giNumActiveThreads;
  31 extern tThread  gThreadZero;
  32 extern tThread  *gActiveThreads;
  33 extern tThread  *gSleepingThreads;
  34 extern tThread  *gDeleteThreads;
  35 extern tThread  *Threads_GetNextToRun(int CPU);
  36 extern void     Threads_Dump();
  37 extern tThread  *Threads_CloneTCB(Uint *Err, Uint Flags);
  38 extern void     Isr7();
  39
  40 // === PROTOTYPES ===
  41 void    ArchThreads_Init();
  42 #if USE_MP
  43 void    MP_StartAP(int CPU);
  44 void    MP_SendIPI(Uint8 APICID, int Vector, int DeliveryMode);
  45 #endif
  46 void    Proc_Start();
  47 tThread *Proc_GetCurThread();
  48 void    Proc_ChangeStack();
  49  int    Proc_Clone(Uint *Err, Uint Flags);
  50 void    Proc_Scheduler();
  51
  52 // === GLOBALS ===
  53 // --- Multiprocessing ---
  54 #if USE_MP
  55 tMPInfo *gMPFloatPtr = NULL;
  56 tIOAPIC *gpMP_LocalAPIC = NULL;
  57 Uint8   gaAPIC_to_CPU[256] = {0};
  58 tCPU    gaCPUs[MAX_CPUS];
  59 #else
  60 tThread *gCurrentThread = NULL;
  61 #endif
  62 #if USE_PAE
  63 Uint32  *gPML4s[4] = NULL;
  64 #endif
  65 tTSS    *gTSSs = NULL;
  66 tTSS    gTSS0 = {0};
  67 // --- Error Recovery ---
  68 char    gaDoubleFaultStack[1024];
  69 tTSS    gDoubleFault_TSS = {
  70         .ESP0 = (Uint)&gaDoubleFaultStack[1023],
  71         .SS0 = 0x10,
  72         .EIP = (Uint)Isr7
  73 };
  74
  75 // === CODE ===
  76 /**
  77  * \fn void ArchThreads_Init()
  78  * \brief Starts the process scheduler
  79  */
  80 void ArchThreads_Init()
  81 {
  82         Uint    pos = 0;
  83
  84         #if USE_MP
  85         tMPTable        *mptable;
  86
  87         // Mark BSP as active
  88         gaCPUs[0].State = 2;
  89
  90         // -- Initialise Multiprocessing
  91         // Find MP Floating Table
  92         // - EBDA/Last 1Kib (640KiB)
  93         for(pos = KERNEL_BASE|0x9F000; pos < (KERNEL_BASE|0xA0000); pos += 16) {
  94                 if( *(Uint*)(pos) == MPPTR_IDENT ) {
  95                         Log("Possible %p", pos);
  96                         if( ByteSum((void*)pos, sizeof(tMPInfo)) != 0 ) continue;
  97                         gMPFloatPtr = (void*)pos;
  98                         break;
  99                 }
 100         }
 101         // - Last KiB (512KiB base mem)
 102         if(!gMPFloatPtr) {
 103                 for(pos = KERNEL_BASE|0x7F000; pos < (KERNEL_BASE|0x80000); pos += 16) {
 104                         if( *(Uint*)(pos) == MPPTR_IDENT ) {
 105                                 Log("Possible %p", pos);
 106                                 if( ByteSum((void*)pos, sizeof(tMPInfo)) != 0 ) continue;
 107                                 gMPFloatPtr = (void*)pos;
 108                                 break;
 109                         }
 110                 }
 111         }
 112         // - BIOS ROM
 113         if(!gMPFloatPtr) {
 114                 for(pos = KERNEL_BASE|0xE0000; pos < (KERNEL_BASE|0x100000); pos += 16) {
 115                         if( *(Uint*)(pos) == MPPTR_IDENT ) {
 116                                 Log("Possible %p", pos);
 117                                 if( ByteSum((void*)pos, sizeof(tMPInfo)) != 0 ) continue;
 118                                 gMPFloatPtr = (void*)pos;
 119                                 break;
 120                         }
 121                 }
 122         }
 123
 124         // If the MP Table Exists, parse it
 125         if(gMPFloatPtr)
 126         {
 127                  int    i;
 128                 tMPTable_Ent    *ents;
 129                 Log("gMPFloatPtr = %p", gMPFloatPtr);
 130                 Log("*gMPFloatPtr = {");
 131                 Log("\t.Sig = 0x%08x", gMPFloatPtr->Sig);
 132                 Log("\t.MPConfig = 0x%08x", gMPFloatPtr->MPConfig);
 133                 Log("\t.Length = 0x%02x", gMPFloatPtr->Length);
 134                 Log("\t.Version = 0x%02x", gMPFloatPtr->Version);
 135                 Log("\t.Checksum = 0x%02x", gMPFloatPtr->Checksum);
 136                 Log("\t.Features = [0x%02x,0x%02x,0x%02x,0x%02x,0x%02x]",
 137                         gMPFloatPtr->Features[0],       gMPFloatPtr->Features[1],
 138                         gMPFloatPtr->Features[2],       gMPFloatPtr->Features[3],
 139                         gMPFloatPtr->Features[4]
 140                         );
 141                 Log("}");
 142
 143                 mptable = (void*)( KERNEL_BASE|gMPFloatPtr->MPConfig );
 144                 Log("mptable = %p", mptable);
 145                 Log("*mptable = {");
 146                 Log("\t.Sig = 0x%08x", mptable->Sig);
 147                 Log("\t.BaseTableLength = 0x%04x", mptable->BaseTableLength);
 148                 Log("\t.SpecRev = 0x%02x", mptable->SpecRev);
 149                 Log("\t.Checksum = 0x%02x", mptable->Checksum);
 150                 Log("\t.OEMID = '%8c'", mptable->OemID);
 151                 Log("\t.ProductID = '%8c'", mptable->ProductID);
 152                 Log("\t.OEMTablePtr = %p'", mptable->OEMTablePtr);
 153                 Log("\t.OEMTableSize = 0x%04x", mptable->OEMTableSize);
 154                 Log("\t.EntryCount = 0x%04x", mptable->EntryCount);
 155                 Log("\t.LocalAPICMemMap = 0x%08x", mptable->LocalAPICMemMap);
 156                 Log("\t.ExtendedTableLen = 0x%04x", mptable->ExtendedTableLen);
 157                 Log("\t.ExtendedTableChecksum = 0x%02x", mptable->ExtendedTableChecksum);
 158                 Log("}");
 159
 160                 gpMP_LocalAPIC = (void*)MM_MapHWPage(mptable->LocalAPICMemMap, 1);
 161
 162                 ents = mptable->Entries;
 163                 giNumCPUs = 0;
 164
 165                 for( i = 0; i < mptable->EntryCount; i ++ )
 166                 {
 167                          int    entSize = 0;
 168                         switch( ents->Type )
 169                         {
 170                         case 0: // Processor
 171                                 entSize = 20;
 172                                 Log("%i: Processor", i);
 173                                 Log("\t.APICID = %i", ents->Proc.APICID);
 174                                 Log("\t.APICVer = 0x%02x", ents->Proc.APICVer);
 175                                 Log("\t.CPUFlags = 0x%02x", ents->Proc.CPUFlags);
 176                                 Log("\t.CPUSignature = 0x%08x", ents->Proc.CPUSignature);
 177                                 Log("\t.FeatureFlags = 0x%08x", ents->Proc.FeatureFlags);
 178
 179                                 // Check if there is too many processors
 180                                 if(giNumCPUs >= MAX_CPUS) {
 181                                         giNumCPUs ++;   // If `giNumCPUs` > MAX_CPUS later, it will be clipped
 182                                         break;
 183                                 }
 184
 185                                 // Initialise CPU Info
 186                                 gaAPIC_to_CPU[ents->Proc.APICID] = giNumCPUs;
 187                                 gaCPUs[giNumCPUs].APICID = ents->Proc.APICID;
 188                                 gaCPUs[giNumCPUs].State = 0;
 189                                 giNumCPUs ++;
 190
 191                                 // Send IPI
 192                                 MP_StartAP( giNumCPUs-1 );
 193
 194                                 break;
 195                         case 1: // Bus
 196                                 entSize = 8;
 197                                 Log("%i: Bus", i);
 198                                 Log("\t.ID = %i", ents->Bus.ID);
 199                                 Log("\t.TypeString = '%6c'", ents->Bus.TypeString);
 200                                 break;
 201                         case 2: // I/O APIC
 202                                 entSize = 8;
 203                                 Log("%i: I/O APIC", i);
 204                                 Log("\t.ID = %i", ents->IOAPIC.ID);
 205                                 Log("\t.Version = 0x%02x", ents->IOAPIC.Version);
 206                                 Log("\t.Flags = 0x%02x", ents->IOAPIC.Flags);
 207                                 Log("\t.Addr = 0x%08x", ents->IOAPIC.Addr);
 208                                 break;
 209                         case 3: // I/O Interrupt Assignment
 210                                 entSize = 8;
 211                                 Log("%i: I/O Interrupt Assignment", i);
 212                                 Log("\t.IntType = %i", ents->IOInt.IntType);
 213                                 Log("\t.Flags = 0x%04x", ents->IOInt.Flags);
 214                                 Log("\t.SourceBusID = 0x%02x", ents->IOInt.SourceBusID);
 215                                 Log("\t.SourceBusIRQ = 0x%02x", ents->IOInt.SourceBusIRQ);
 216                                 Log("\t.DestAPICID = 0x%02x", ents->IOInt.DestAPICID);
 217                                 Log("\t.DestAPICIRQ = 0x%02x", ents->IOInt.DestAPICIRQ);
 218                                 break;
 219                         case 4: // Local Interrupt Assignment
 220                                 entSize = 8;
 221                                 Log("%i: Local Interrupt Assignment", i);
 222                                 Log("\t.IntType = %i", ents->LocalInt.IntType);
 223                                 Log("\t.Flags = 0x%04x", ents->LocalInt.Flags);
 224                                 Log("\t.SourceBusID = 0x%02x", ents->LocalInt.SourceBusID);
 225                                 Log("\t.SourceBusIRQ = 0x%02x", ents->LocalInt.SourceBusIRQ);
 226                                 Log("\t.DestLocalAPICID = 0x%02x", ents->LocalInt.DestLocalAPICID);
 227                                 Log("\t.DestLocalAPICIRQ = 0x%02x", ents->LocalInt.DestLocalAPICIRQ);
 228                                 break;
 229                         default:
 230                                 Log("%i: Unknown (%i)", i, ents->Type);
 231                                 break;
 232                         }
 233                         ents = (void*)( (Uint)ents + entSize );
 234                 }
 235
 236                 if( giNumCPUs > MAX_CPUS ) {
 237                         Warning("Too many CPUs detected (%i), only using %i of them", giNumCPUs, MAX_CPUS);
 238                 }
 239
 240                 Panic("Uh oh... MP Table Parsing is unimplemented\n");
 241         }
 242         else {
 243                 Log("No MP Table was found, assuming uniprocessor\n");
 244                 giNumCPUs = 1;
 245                 gTSSs = &gTSS0;
 246         }
 247         #else
 248         giNumCPUs = 1;
 249         gTSSs = &gTSS0;
 250         #endif
 251
 252         // Initialise Double Fault TSS
 253         /*
 254         gGDT[5].LimitLow = sizeof(tTSS);
 255         gGDT[5].LimitHi = 0;
 256         gGDT[5].Access = 0x89;  // Type
 257         gGDT[5].Flags = 0x4;
 258         */
 259         gGDT[5].BaseLow = (Uint)&gDoubleFault_TSS & 0xFFFF;
 260         gGDT[5].BaseMid = (Uint)&gDoubleFault_TSS >> 16;
 261         gGDT[5].BaseHi = (Uint)&gDoubleFault_TSS >> 24;
 262
 263         #if USE_MP
 264         // Initialise Normal TSS(s)
 265         for(pos=0;pos<giNumCPUs;pos++)
 266         {
 267         #else
 268         pos = 0;
 269         #endif
 270                 gTSSs[pos].SS0 = 0x10;
 271                 gTSSs[pos].ESP0 = 0;    // Set properly by scheduler
 272                 gGDT[6+pos].BaseLow = ((Uint)(&gTSSs[pos])) & 0xFFFF;
 273                 gGDT[6+pos].BaseMid = ((Uint)(&gTSSs[pos])) >> 16;
 274                 gGDT[6+pos].BaseHi = ((Uint)(&gTSSs[pos])) >> 24;
 275         #if USE_MP
 276         }
 277         for(pos=0;pos<giNumCPUs;pos++) {
 278         #endif
 279                 __asm__ __volatile__ ("ltr %%ax"::"a"(0x30+pos*8));
 280         #if USE_MP
 281         }
 282         #endif
 283
 284         #if USE_MP
 285         gaCPUs[0].Current = &gThreadZero;
 286         #else
 287         gCurrentThread = &gThreadZero;
 288         #endif
 289
 290         #if USE_PAE
 291         gThreadZero.MemState.PDP[0] = 0;
 292         gThreadZero.MemState.PDP[1] = 0;
 293         gThreadZero.MemState.PDP[2] = 0;
 294         #else
 295         gThreadZero.MemState.CR3 = (Uint)gaInitPageDir - KERNEL_BASE;
 296         #endif
 297
 298         // Set timer frequency
 299         outb(0x43, 0x34);       // Set Channel 0, Low/High, Rate Generator
 300         outb(0x40, TIMER_DIVISOR&0xFF); // Low Byte of Divisor
 301         outb(0x40, (TIMER_DIVISOR>>8)&0xFF);    // High Byte
 302
 303         // Create Per-Process Data Block
 304         MM_Allocate(MM_PPD_CFG);
 305
 306         // Change Stacks
 307         Proc_ChangeStack();
 308 }
 309
 310 #if USE_MP
 311 void MP_StartAP(int CPU)
 312 {
 313         Log("Starting AP %i (APIC %i)", CPU, gaCPUs[CPU].APICID);
 314         // Set location of AP startup code and mark for a warm restart
 315         *(Uint16*)(KERNEL_BASE|0x467) = (Uint)&APStartup - (KERNEL_BASE|0xFFFF0);
 316         *(Uint16*)(KERNEL_BASE|0x469) = 0xFFFF;
 317         outb(0x70, 0x0F);       outb(0x71, 0x0A);       // Warm Reset
 318         MP_SendIPI(gaCPUs[CPU].APICID, 0, 5);
 319 }
 320
 321 void MP_SendIPI(Uint8 APICID, int Vector, int DeliveryMode)
 322 {
 323         Uint32  addr = (Uint)gpMP_LocalAPIC + 0x20 + (APICID<<3);
 324
 325         *(Uint32*)addr = ((DeliveryMode & 7) << 8) | (Vector & 0xFF);
 326 }
 327 #endif
 328
 329 /**
 330  * \fn void Proc_Start()
 331  * \brief Start process scheduler
 332  */
 333 void Proc_Start()
 334 {
 335         // Start Interrupts (and hence scheduler)
 336         __asm__ __volatile__("sti");
 337 }
 338
 339 /**
 340  * \fn tThread *Proc_GetCurThread()
 341  * \brief Gets the current thread
 342  */
 343 tThread *Proc_GetCurThread()
 344 {
 345         #if USE_MP
 346         gpMP_LocalAPIC->Addr = 0;
 347         return gaCPUs[ gaAPIC_to_CPU[gpMP_LocalAPIC->Value.Byte] ].Current;
 348         #else
 349         return gCurrentThread;
 350         #endif
 351 }
 352
 353 /**
 354  * \fn void Proc_ChangeStack()
 355  * \brief Swaps the current stack for a new one (in the proper stack reigon)
 356  */
 357 void Proc_ChangeStack()
 358 {
 359         Uint    esp, ebp;
 360         Uint    tmpEbp, oldEsp;
 361         Uint    curBase, newBase;
 362
 363         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 364         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 365
 366         oldEsp = esp;
 367
 368         // Create new KStack
 369         newBase = MM_NewKStack();
 370         // Check for errors
 371         if(newBase == 0) {
 372                 Panic("What the?? Unable to allocate space for initial kernel stack");
 373                 return;
 374         }
 375
 376         curBase = (Uint)&Kernel_Stack_Top;
 377
 378         LOG("curBase = 0x%x, newBase = 0x%x", curBase, newBase);
 379
 380         // Get ESP as a used size
 381         esp = curBase - esp;
 382         LOG("memcpy( %p, %p, 0x%x )", (void*)(newBase - esp), (void*)(curBase - esp), esp );
 383         // Copy used stack
 384         memcpy( (void*)(newBase - esp), (void*)(curBase - esp), esp );
 385         // Get ESP as an offset in the new stack
 386         esp = newBase - esp;
 387         // Adjust EBP
 388         ebp = newBase - (curBase - ebp);
 389
 390         // Repair EBPs & Stack Addresses
 391         // Catches arguments also, but may trash stack-address-like values
 392         for(tmpEbp = esp; tmpEbp < newBase; tmpEbp += 4)
 393         {
 394                 if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < curBase)
 395                         *(Uint*)tmpEbp += newBase - curBase;
 396         }
 397
 398         Proc_GetCurThread()->KernelStack = newBase;
 399
 400         __asm__ __volatile__ ("mov %0, %%esp"::"r"(esp));
 401         __asm__ __volatile__ ("mov %0, %%ebp"::"r"(ebp));
 402 }
 403
 404 /**
 405  * \fn int Proc_Clone(Uint *Err, Uint Flags)
 406  * \brief Clone the current process
 407  */
 408 int Proc_Clone(Uint *Err, Uint Flags)
 409 {
 410         tThread *newThread;
 411         tThread *cur = Proc_GetCurThread();
 412         Uint    eip, esp, ebp;
 413
 414         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 415         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 416
 417         newThread = Threads_CloneTCB(Err, Flags);
 418         if(!newThread)  return -1;
 419
 420         // Initialise Memory Space (New Addr space or kernel stack)
 421         if(Flags & CLONE_VM) {
 422                 newThread->MemState.CR3 = MM_Clone();
 423                 newThread->KernelStack = cur->KernelStack;
 424         } else {
 425                 Uint    tmpEbp, oldEsp = esp;
 426
 427                 // Set CR3
 428                 newThread->MemState.CR3 = cur->MemState.CR3;
 429
 430                 // Create new KStack
 431                 newThread->KernelStack = MM_NewKStack();
 432                 // Check for errors
 433                 if(newThread->KernelStack == 0) {
 434                         free(newThread);
 435                         return -1;
 436                 }
 437
 438                 // Get ESP as a used size
 439                 esp = cur->KernelStack - esp;
 440                 // Copy used stack
 441                 memcpy( (void*)(newThread->KernelStack - esp), (void*)(cur->KernelStack - esp), esp );
 442                 // Get ESP as an offset in the new stack
 443                 esp = newThread->KernelStack - esp;
 444                 // Adjust EBP
 445                 ebp = newThread->KernelStack - (cur->KernelStack - ebp);
 446
 447                 // Repair EBPs & Stack Addresses
 448                 // Catches arguments also, but may trash stack-address-like values
 449                 for(tmpEbp = esp; tmpEbp < newThread->KernelStack; tmpEbp += 4)
 450                 {
 451                         if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < cur->KernelStack)
 452                                 *(Uint*)tmpEbp += newThread->KernelStack - cur->KernelStack;
 453                 }
 454         }
 455
 456         // Save core machine state
 457         newThread->SavedState.ESP = esp;
 458         newThread->SavedState.EBP = ebp;
 459         eip = GetEIP();
 460         if(eip == SWITCH_MAGIC) {
 461                 outb(0x20, 0x20);       // ACK Timer and return as child
 462                 return 0;
 463         }
 464
 465         // Set EIP as parent
 466         newThread->SavedState.EIP = eip;
 467
 468         // Lock list and add to active
 469         Threads_AddActive(newThread);
 470
 471         return newThread->TID;
 472 }
 473
 474 /**
 475  * \fn int Proc_SpawnWorker()
 476  * \brief Spawns a new worker thread
 477  */
 478 int Proc_SpawnWorker()
 479 {
 480         tThread *new, *cur;
 481         Uint    eip, esp, ebp;
 482
 483         cur = Proc_GetCurThread();
 484
 485         // Create new thread
 486         new = malloc( sizeof(tThread) );
 487         if(!new) {
 488                 Warning("Proc_SpawnWorker - Out of heap space!\n");
 489                 return -1;
 490         }
 491         memcpy(new, &gThreadZero, sizeof(tThread));
 492         // Set Thread ID
 493         new->TID = giNextTID++;
 494         // Create a new worker stack (in PID0's address space)
 495         // The stack is relocated by this code
 496         new->KernelStack = MM_NewWorkerStack();
 497
 498         // Get ESP and EBP based in the new stack
 499         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 500         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 501         esp = new->KernelStack - (cur->KernelStack - esp);
 502         ebp = new->KernelStack - (cur->KernelStack - ebp);
 503
 504         // Save core machine state
 505         new->SavedState.ESP = esp;
 506         new->SavedState.EBP = ebp;
 507         eip = GetEIP();
 508         if(eip == SWITCH_MAGIC) {
 509                 outb(0x20, 0x20);       // ACK Timer and return as child
 510                 return 0;
 511         }
 512
 513         // Set EIP as parent
 514         new->SavedState.EIP = eip;
 515         // Mark as active
 516         new->Status = THREAD_STAT_ACTIVE;
 517         Threads_AddActive( new );
 518
 519         return new->TID;
 520 }
 521
 522 /**
 523  * \fn Uint Proc_MakeUserStack()
 524  * \brief Creates a new user stack
 525  */
 526 Uint Proc_MakeUserStack()
 527 {
 528          int    i;
 529         Uint    base = USER_STACK_TOP - USER_STACK_SZ;
 530
 531         // Check Prospective Space
 532         for( i = USER_STACK_SZ >> 12; i--; )
 533                 if( MM_GetPhysAddr( base + (i<<12) ) != 0 )
 534                         break;
 535
 536         if(i != -1)     return 0;
 537
 538         // Allocate Stack - Allocate incrementally to clean up MM_Dump output
 539         for( i = 0; i < USER_STACK_SZ/4069; i++ )
 540                 MM_Allocate( base + (i<<12) );
 541
 542         return base + USER_STACK_SZ;
 543 }
 544
 545
 546 /**
 547  * \fn void Proc_StartUser(Uint Entrypoint, Uint *Bases, int ArgC, char **ArgV, char **EnvP, int DataSize)
 548  * \brief Starts a user task
 549  */
 550 void Proc_StartUser(Uint Entrypoint, Uint *Bases, int ArgC, char **ArgV, char **EnvP, int DataSize)
 551 {
 552         Uint    *stack = (void*)Proc_MakeUserStack();
 553          int    i;
 554         Uint    delta;
 555         Uint16  ss, cs;
 556
 557         LOG("stack = 0x%x", stack);
 558
 559         // Copy Arguments
 560         stack = (void*)( (Uint)stack - DataSize );
 561         memcpy( stack, ArgV, DataSize );
 562
 563         // Adjust Arguments and environment
 564         delta = (Uint)stack - (Uint)ArgV;
 565         ArgV = (char**)stack;
 566         for( i = 0; ArgV[i]; i++ )      ArgV[i] += delta;
 567         i ++;
 568         EnvP = &ArgV[i];
 569         for( i = 0; EnvP[i]; i++ )      EnvP[i] += delta;
 570
 571         // User Mode Segments
 572         ss = 0x23;      cs = 0x1B;
 573
 574         // Arguments
 575         *--stack = (Uint)EnvP;
 576         *--stack = (Uint)ArgV;
 577         *--stack = (Uint)ArgC;
 578         while(*Bases)
 579                 *--stack = *Bases++;
 580         *--stack = 0;   // Return Address
 581         delta = (Uint)stack;    // Reuse delta to save SP
 582
 583         *--stack = ss;          //Stack Segment
 584         *--stack = delta;       //Stack Pointer
 585         *--stack = 0x0202;      //EFLAGS (Resvd (0x2) and IF (0x20))
 586         *--stack = cs;          //Code Segment
 587         *--stack = Entrypoint;  //EIP
 588         //PUSHAD
 589         *--stack = 0xAAAAAAAA;  // eax
 590         *--stack = 0xCCCCCCCC;  // ecx
 591         *--stack = 0xDDDDDDDD;  // edx
 592         *--stack = 0xBBBBBBBB;  // ebx
 593         *--stack = 0xD1D1D1D1;  // edi
 594         *--stack = 0x54545454;  // esp - NOT POPED
 595         *--stack = 0x51515151;  // esi
 596         *--stack = 0xB4B4B4B4;  // ebp
 597         //Individual PUSHs
 598         *--stack = ss;  // ds
 599         *--stack = ss;  // es
 600         *--stack = ss;  // fs
 601         *--stack = ss;  // gs
 602
 603         __asm__ __volatile__ (
 604         "mov %%eax,%%esp;\n\t"  // Set stack pointer
 605         "pop %%gs;\n\t"
 606         "pop %%fs;\n\t"
 607         "pop %%es;\n\t"
 608         "pop %%ds;\n\t"
 609         "popa;\n\t"
 610         "iret;\n\t" : : "a" (stack));
 611         for(;;);
 612 }
 613
 614 /**
 615  * \fn int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 616  * \brief Demotes a process to a lower permission level
 617  * \param Err   Pointer to user's errno
 618  * \param Dest  New Permission Level
 619  * \param Regs  Pointer to user's register structure
 620  */
 621 int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 622 {
 623          int    cpl = Regs->cs & 3;
 624         // Sanity Check
 625         if(Dest > 3 || Dest < 0) {
 626                 *Err = -EINVAL;
 627                 return -1;
 628         }
 629
 630         // Permission Check
 631         if(cpl > Dest) {
 632                 *Err = -EACCES;
 633                 return -1;
 634         }
 635
 636         // Change the Segment Registers
 637         Regs->cs = (((Dest+1)<<4) | Dest) - 8;
 638         Regs->ss = ((Dest+1)<<4) | Dest;
 639         // Check if the GP Segs are GDT, then change them
 640         if(!(Regs->ds & 4))     Regs->ds = ((Dest+1)<<4) | Dest;
 641         if(!(Regs->es & 4))     Regs->es = ((Dest+1)<<4) | Dest;
 642         if(!(Regs->fs & 4))     Regs->fs = ((Dest+1)<<4) | Dest;
 643         if(!(Regs->gs & 4))     Regs->gs = ((Dest+1)<<4) | Dest;
 644
 645         return 0;
 646 }
 647
 648 /**
 649  * \fn void Proc_Scheduler(int CPU)
 650  * \brief Swap current thread and clears dead threads
 651  */
 652 void Proc_Scheduler(int CPU)
 653 {
 654         Uint    esp, ebp, eip;
 655         tThread *thread;
 656
 657         // If the spinlock is set, let it complete
 658         if(giThreadListLock)    return;
 659
 660         // Clear Delete Queue
 661         while(gDeleteThreads)
 662         {
 663                 thread = gDeleteThreads->Next;
 664                 if(gDeleteThreads->IsLocked) {  // Only free if structure is unused
 665                         gDeleteThreads->Status = THREAD_STAT_NULL;
 666                         free( gDeleteThreads );
 667                 }
 668                 gDeleteThreads = thread;
 669         }
 670
 671         // Check if there is any tasks running
 672         if(giNumActiveThreads == 0) {
 673                 Log("No Active threads, sleeping");
 674                 __asm__ __volatile__ ("hlt");
 675                 return;
 676         }
 677
 678         // Get current thread
 679         #if USE_MP
 680         thread = gaCPUs[CPU].Current;
 681         #else
 682         curThread = gCurrentThread;
 683         #endif
 684
 685         // Reduce remaining quantum and continue timeslice if non-zero
 686         if(thread->Remaining--) return;
 687         // Reset quantum for next call
 688         thread->Remaining = thread->Quantum;
 689
 690         // Get machine state
 691         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 692         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 693         eip = GetEIP();
 694         if(eip == SWITCH_MAGIC) return; // Check if a switch happened
 695
 696         // Save machine state
 697         thread->SavedState.ESP = esp;
 698         thread->SavedState.EBP = ebp;
 699         thread->SavedState.EIP = eip;
 700
 701         // Get next thread
 702         thread = Threads_GetNextToRun(CPU);
 703
 704         // Error Check
 705         if(thread == NULL) {
 706                 Warning("Hmm... Threads_GetNextToRun returned NULL, I don't think this should happen.\n");
 707                 return;
 708         }
 709
 710         #if DEBUG_TRACE_SWITCH
 711         Log("Switching to task %i, CR3 = 0x%x, EIP = %p",
 712                 thread->TID,
 713                 thread->MemState.CR3,
 714                 thread->SavedState.EIP
 715                 );
 716         #endif
 717
 718         // Set current thread
 719         #if USE_MP
 720         gaCPUs[CPU].Current = thread;
 721         #else
 722         gCurrentThread = thread;
 723         #endif
 724
 725         // Update Kernel Stack pointer
 726         gTSSs[CPU].ESP0 = thread->KernelStack;
 727
 728         // Set address space
 729         #if USE_PAE
 730         # error "Todo: Implement PAE Address space switching"
 731         #else
 732                 __asm__ __volatile__ ("mov %0, %%cr3"::"a"(thread->MemState.CR3));
 733         #endif
 734         // Switch threads
 735         __asm__ __volatile__ (
 736                 "mov %1, %%esp\n\t"     // Restore ESP
 737                 "mov %2, %%ebp\n\t"     // and EBP
 738                 "jmp *%3" : :   // And return to where we saved state (Proc_Clone or Proc_Scheduler)
 739                 "a"(SWITCH_MAGIC), "b"(thread->SavedState.ESP),
 740                 "d"(thread->SavedState.EBP), "c"(thread->SavedState.EIP)
 741                 );
 742         for(;;);        // Shouldn't reach here
 743 }
 744
 745 // === EXPORTS ===
 746 EXPORT(Proc_SpawnWorker);