Kernel/arch/x86/proc.c

   1 /*
   2  * AcessOS Microkernel Version
   3  * proc.c
   4  */
   5 #include <acess.h>
   6 #include <proc.h>
   7 #include <desctab.h>
   8 #include <mm_virt.h>
   9 #include <errno.h>
  10 #if USE_MP
  11 # include <mp.h>
  12 #endif
  13
  14 // === FLAGS ===
  15 #define DEBUG_TRACE_SWITCH      0
  16
  17 // === CONSTANTS ===
  18 #define SWITCH_MAGIC    0xFFFACE55      // There is no code in this area
  19 // Base is 1193182
  20 #define TIMER_DIVISOR   11931   //~100Hz
  21
  22 // === IMPORTS ===
  23 extern tGDT     gGDT[];
  24 extern tIDT     gIDT[];
  25 extern void APStartup();        // 16-bit AP startup code
  26 extern Uint     GetEIP();       // start.asm
  27 extern Uint32   gaInitPageDir[1024];    // start.asm
  28 extern void     Kernel_Stack_Top;
  29 extern volatile int     giThreadListLock;
  30 extern int      giNumCPUs;
  31 extern int      giNextTID;
  32 extern int      giTotalTickets;
  33 extern int      giNumActiveThreads;
  34 extern tThread  gThreadZero;
  35 extern tThread  *gActiveThreads;
  36 extern tThread  *gSleepingThreads;
  37 extern tThread  *gDeleteThreads;
  38 extern tThread  *Threads_GetNextToRun(int CPU);
  39 extern void     Threads_Dump();
  40 extern tThread  *Threads_CloneTCB(Uint *Err, Uint Flags);
  41 extern void     Isr8(); // Double Fault
  42 extern void     Proc_AlterUserReturnAddr();
  43
  44 // === PROTOTYPES ===
  45 void    ArchThreads_Init();
  46 #if USE_MP
  47 void    MP_StartAP(int CPU);
  48 void    MP_SendIPI(Uint8 APICID, int Vector, int DeliveryMode);
  49 #endif
  50 void    Proc_Start();
  51 tThread *Proc_GetCurThread();
  52 void    Proc_ChangeStack();
  53  int    Proc_Clone(Uint *Err, Uint Flags);
  54 void    Proc_StartProcess(Uint16 SS, Uint Stack, Uint Flags, Uint16 CS, Uint IP);
  55 void    Proc_CallFaultHandler(tThread *Thread);
  56 void    Proc_Scheduler();
  57
  58 // === GLOBALS ===
  59 // --- Multiprocessing ---
  60 #if USE_MP
  61 volatile int    giNumInitingCPUs = 0;
  62 tMPInfo *gMPFloatPtr = NULL;
  63 tAPIC   *gpMP_LocalAPIC = NULL;
  64 Uint8   gaAPIC_to_CPU[256] = {0};
  65 tCPU    gaCPUs[MAX_CPUS];
  66 #else
  67 tThread *gCurrentThread = NULL;
  68 #endif
  69 #if USE_PAE
  70 Uint32  *gPML4s[4] = NULL;
  71 #endif
  72 tTSS    *gTSSs = NULL;
  73 tTSS    gTSS0 = {0};
  74 // --- Error Recovery ---
  75 char    gaDoubleFaultStack[1024];
  76 tTSS    gDoubleFault_TSS = {
  77         .ESP0 = (Uint)&gaDoubleFaultStack[1023],
  78         .SS0 = 0x10,
  79         .CR3 = (Uint)gaInitPageDir - KERNEL_BASE,
  80         .EIP = (Uint)Isr8,
  81         .ESP = (Uint)&gaDoubleFaultStack[1023],
  82         .CS = 0x08,     .SS = 0x10,
  83         .DS = 0x10,     .ES = 0x10,
  84         .FS = 0x10,     .GS = 0x10,
  85 };
  86
  87 // === CODE ===
  88 /**
  89  * \fn void ArchThreads_Init()
  90  * \brief Starts the process scheduler
  91  */
  92 void ArchThreads_Init()
  93 {
  94         Uint    pos = 0;
  95
  96         #if USE_MP
  97         tMPTable        *mptable;
  98
  99         // Mark BSP as active
 100         gaCPUs[0].State = 2;
 101
 102         // -- Initialise Multiprocessing
 103         // Find MP Floating Table
 104         // - EBDA/Last 1Kib (640KiB)
 105         for(pos = KERNEL_BASE|0x9F000; pos < (KERNEL_BASE|0xA0000); pos += 16) {
 106                 if( *(Uint*)(pos) == MPPTR_IDENT ) {
 107                         Log("Possible %p", pos);
 108                         if( ByteSum((void*)pos, sizeof(tMPInfo)) != 0 ) continue;
 109                         gMPFloatPtr = (void*)pos;
 110                         break;
 111                 }
 112         }
 113         // - Last KiB (512KiB base mem)
 114         if(!gMPFloatPtr) {
 115                 for(pos = KERNEL_BASE|0x7F000; pos < (KERNEL_BASE|0x80000); pos += 16) {
 116                         if( *(Uint*)(pos) == MPPTR_IDENT ) {
 117                                 Log("Possible %p", pos);
 118                                 if( ByteSum((void*)pos, sizeof(tMPInfo)) != 0 ) continue;
 119                                 gMPFloatPtr = (void*)pos;
 120                                 break;
 121                         }
 122                 }
 123         }
 124         // - BIOS ROM
 125         if(!gMPFloatPtr) {
 126                 for(pos = KERNEL_BASE|0xE0000; pos < (KERNEL_BASE|0x100000); pos += 16) {
 127                         if( *(Uint*)(pos) == MPPTR_IDENT ) {
 128                                 Log("Possible %p", pos);
 129                                 if( ByteSum((void*)pos, sizeof(tMPInfo)) != 0 ) continue;
 130                                 gMPFloatPtr = (void*)pos;
 131                                 break;
 132                         }
 133                 }
 134         }
 135
 136         // If the MP Table Exists, parse it
 137         if(gMPFloatPtr)
 138         {
 139                  int    i;
 140                 tMPTable_Ent    *ents;
 141                 Log("gMPFloatPtr = %p", gMPFloatPtr);
 142                 Log("*gMPFloatPtr = {");
 143                 Log("\t.Sig = 0x%08x", gMPFloatPtr->Sig);
 144                 Log("\t.MPConfig = 0x%08x", gMPFloatPtr->MPConfig);
 145                 Log("\t.Length = 0x%02x", gMPFloatPtr->Length);
 146                 Log("\t.Version = 0x%02x", gMPFloatPtr->Version);
 147                 Log("\t.Checksum = 0x%02x", gMPFloatPtr->Checksum);
 148                 Log("\t.Features = [0x%02x,0x%02x,0x%02x,0x%02x,0x%02x]",
 149                         gMPFloatPtr->Features[0],       gMPFloatPtr->Features[1],
 150                         gMPFloatPtr->Features[2],       gMPFloatPtr->Features[3],
 151                         gMPFloatPtr->Features[4]
 152                         );
 153                 Log("}");
 154
 155                 mptable = (void*)( KERNEL_BASE|gMPFloatPtr->MPConfig );
 156                 Log("mptable = %p", mptable);
 157                 Log("*mptable = {");
 158                 Log("\t.Sig = 0x%08x", mptable->Sig);
 159                 Log("\t.BaseTableLength = 0x%04x", mptable->BaseTableLength);
 160                 Log("\t.SpecRev = 0x%02x", mptable->SpecRev);
 161                 Log("\t.Checksum = 0x%02x", mptable->Checksum);
 162                 Log("\t.OEMID = '%8c'", mptable->OemID);
 163                 Log("\t.ProductID = '%8c'", mptable->ProductID);
 164                 Log("\t.OEMTablePtr = %p'", mptable->OEMTablePtr);
 165                 Log("\t.OEMTableSize = 0x%04x", mptable->OEMTableSize);
 166                 Log("\t.EntryCount = 0x%04x", mptable->EntryCount);
 167                 Log("\t.LocalAPICMemMap = 0x%08x", mptable->LocalAPICMemMap);
 168                 Log("\t.ExtendedTableLen = 0x%04x", mptable->ExtendedTableLen);
 169                 Log("\t.ExtendedTableChecksum = 0x%02x", mptable->ExtendedTableChecksum);
 170                 Log("}");
 171
 172                 gpMP_LocalAPIC = (void*)MM_MapHWPage(mptable->LocalAPICMemMap, 1);
 173
 174                 ents = mptable->Entries;
 175                 giNumCPUs = 0;
 176
 177                 for( i = 0; i < mptable->EntryCount; i ++ )
 178                 {
 179                          int    entSize = 0;
 180                         switch( ents->Type )
 181                         {
 182                         case 0: // Processor
 183                                 entSize = 20;
 184                                 Log("%i: Processor", i);
 185                                 Log("\t.APICID = %i", ents->Proc.APICID);
 186                                 Log("\t.APICVer = 0x%02x", ents->Proc.APICVer);
 187                                 Log("\t.CPUFlags = 0x%02x", ents->Proc.CPUFlags);
 188                                 Log("\t.CPUSignature = 0x%08x", ents->Proc.CPUSignature);
 189                                 Log("\t.FeatureFlags = 0x%08x", ents->Proc.FeatureFlags);
 190
 191
 192                                 if( !(ents->Proc.CPUFlags & 1) ) {
 193                                         Log("DISABLED");
 194                                         break;
 195                                 }
 196
 197                                 // Check if there is too many processors
 198                                 if(giNumCPUs >= MAX_CPUS) {
 199                                         giNumCPUs ++;   // If `giNumCPUs` > MAX_CPUS later, it will be clipped
 200                                         break;
 201                                 }
 202
 203                                 // Initialise CPU Info
 204                                 gaAPIC_to_CPU[ents->Proc.APICID] = giNumCPUs;
 205                                 gaCPUs[giNumCPUs].APICID = ents->Proc.APICID;
 206                                 gaCPUs[giNumCPUs].State = 0;
 207                                 giNumCPUs ++;
 208
 209                                 // Send IPI
 210                                 if( !(ents->Proc.CPUFlags & 2) )
 211                                 {
 212                                         MP_StartAP( giNumCPUs-1 );
 213                                 }
 214
 215                                 break;
 216                         case 1: // Bus
 217                                 entSize = 8;
 218                                 Log("%i: Bus", i);
 219                                 Log("\t.ID = %i", ents->Bus.ID);
 220                                 Log("\t.TypeString = '%6c'", ents->Bus.TypeString);
 221                                 break;
 222                         case 2: // I/O APIC
 223                                 entSize = 8;
 224                                 Log("%i: I/O APIC", i);
 225                                 Log("\t.ID = %i", ents->IOAPIC.ID);
 226                                 Log("\t.Version = 0x%02x", ents->IOAPIC.Version);
 227                                 Log("\t.Flags = 0x%02x", ents->IOAPIC.Flags);
 228                                 Log("\t.Addr = 0x%08x", ents->IOAPIC.Addr);
 229                                 break;
 230                         case 3: // I/O Interrupt Assignment
 231                                 entSize = 8;
 232                                 Log("%i: I/O Interrupt Assignment", i);
 233                                 Log("\t.IntType = %i", ents->IOInt.IntType);
 234                                 Log("\t.Flags = 0x%04x", ents->IOInt.Flags);
 235                                 Log("\t.SourceBusID = 0x%02x", ents->IOInt.SourceBusID);
 236                                 Log("\t.SourceBusIRQ = 0x%02x", ents->IOInt.SourceBusIRQ);
 237                                 Log("\t.DestAPICID = 0x%02x", ents->IOInt.DestAPICID);
 238                                 Log("\t.DestAPICIRQ = 0x%02x", ents->IOInt.DestAPICIRQ);
 239                                 break;
 240                         case 4: // Local Interrupt Assignment
 241                                 entSize = 8;
 242                                 Log("%i: Local Interrupt Assignment", i);
 243                                 Log("\t.IntType = %i", ents->LocalInt.IntType);
 244                                 Log("\t.Flags = 0x%04x", ents->LocalInt.Flags);
 245                                 Log("\t.SourceBusID = 0x%02x", ents->LocalInt.SourceBusID);
 246                                 Log("\t.SourceBusIRQ = 0x%02x", ents->LocalInt.SourceBusIRQ);
 247                                 Log("\t.DestLocalAPICID = 0x%02x", ents->LocalInt.DestLocalAPICID);
 248                                 Log("\t.DestLocalAPICIRQ = 0x%02x", ents->LocalInt.DestLocalAPICIRQ);
 249                                 break;
 250                         default:
 251                                 Log("%i: Unknown (%i)", i, ents->Type);
 252                                 break;
 253                         }
 254                         ents = (void*)( (Uint)ents + entSize );
 255                 }
 256
 257                 if( giNumCPUs > MAX_CPUS ) {
 258                         Warning("Too many CPUs detected (%i), only using %i of them", giNumCPUs, MAX_CPUS);
 259                         giNumCPUs = MAX_CPUS;
 260                 }
 261
 262                 while( giNumInitingCPUs )
 263                         MM_FinishVirtualInit();
 264
 265                 Panic("Uh oh... MP Table Parsing is unimplemented\n");
 266         }
 267         else {
 268                 Log("No MP Table was found, assuming uniprocessor\n");
 269                 giNumCPUs = 1;
 270                 gTSSs = &gTSS0;
 271         }
 272         #else
 273         giNumCPUs = 1;
 274         gTSSs = &gTSS0;
 275         MM_FinishVirtualInit();
 276         #endif
 277
 278         // Initialise Double Fault TSS
 279         /*
 280         gGDT[5].LimitLow = sizeof(tTSS);
 281         gGDT[5].LimitHi = 0;
 282         gGDT[5].Access = 0x89;  // Type
 283         gGDT[5].Flags = 0x4;
 284         */
 285         gGDT[5].BaseLow = (Uint)&gDoubleFault_TSS & 0xFFFF;
 286         gGDT[5].BaseMid = (Uint)&gDoubleFault_TSS >> 16;
 287         gGDT[5].BaseHi = (Uint)&gDoubleFault_TSS >> 24;
 288
 289         Log_Debug("Proc", "gIDT[8] = {OffsetLo:%04x, CS:%04x, Flags:%04x, OffsetHi:%04x}",
 290                 gIDT[8].OffsetLo, gIDT[8].CS, gIDT[8].Flags, gIDT[8].OffsetHi);
 291         gIDT[8].OffsetLo = 0;
 292         gIDT[8].CS = 5<<3;
 293         gIDT[8].Flags = 0x8500;
 294         gIDT[8].OffsetHi = 0;
 295         Log_Debug("Proc", "gIDT[8] = {OffsetLo:%04x, CS:%04x, Flags:%04x, OffsetHi:%04x}",
 296                 gIDT[8].OffsetLo, gIDT[8].CS, gIDT[8].Flags, gIDT[8].OffsetHi);
 297
 298         //__asm__ __volatile__ ("xchg %bx, %bx");
 299
 300         #if USE_MP
 301         // Initialise Normal TSS(s)
 302         for(pos=0;pos<giNumCPUs;pos++)
 303         {
 304         #else
 305         pos = 0;
 306         #endif
 307                 gTSSs[pos].SS0 = 0x10;
 308                 gTSSs[pos].ESP0 = 0;    // Set properly by scheduler
 309                 gGDT[6+pos].BaseLow = ((Uint)(&gTSSs[pos])) & 0xFFFF;
 310                 gGDT[6+pos].BaseMid = ((Uint)(&gTSSs[pos])) >> 16;
 311                 gGDT[6+pos].BaseHi = ((Uint)(&gTSSs[pos])) >> 24;
 312         #if USE_MP
 313         }
 314         for(pos=0;pos<giNumCPUs;pos++) {
 315         #endif
 316                 __asm__ __volatile__ ("ltr %%ax"::"a"(0x30+pos*8));
 317         #if USE_MP
 318         }
 319         #endif
 320
 321         #if USE_MP
 322         gaCPUs[0].Current = &gThreadZero;
 323         #else
 324         gCurrentThread = &gThreadZero;
 325         #endif
 326
 327         #if USE_PAE
 328         gThreadZero.MemState.PDP[0] = 0;
 329         gThreadZero.MemState.PDP[1] = 0;
 330         gThreadZero.MemState.PDP[2] = 0;
 331         #else
 332         gThreadZero.MemState.CR3 = (Uint)gaInitPageDir - KERNEL_BASE;
 333         #endif
 334
 335         // Set timer frequency
 336         outb(0x43, 0x34);       // Set Channel 0, Low/High, Rate Generator
 337         outb(0x40, TIMER_DIVISOR&0xFF); // Low Byte of Divisor
 338         outb(0x40, (TIMER_DIVISOR>>8)&0xFF);    // High Byte
 339
 340         // Create Per-Process Data Block
 341         MM_Allocate(MM_PPD_CFG);
 342
 343         // Change Stacks
 344         Proc_ChangeStack();
 345 }
 346
 347 #if USE_MP
 348 void MP_StartAP(int CPU)
 349 {
 350         Log("Starting AP %i (APIC %i)", CPU, gaCPUs[CPU].APICID);
 351         // Set location of AP startup code and mark for a warm restart
 352         *(Uint16*)(KERNEL_BASE|0x467) = (Uint)&APStartup - (KERNEL_BASE|0xFFFF0);
 353         *(Uint16*)(KERNEL_BASE|0x469) = 0xFFFF;
 354         outb(0x70, 0x0F);       outb(0x71, 0x0A);       // Warm Reset
 355         MP_SendIPI(gaCPUs[CPU].APICID, 0, 5);
 356         giNumInitingCPUs ++;
 357 }
 358
 359 void MP_SendIPI(Uint8 APICID, int Vector, int DeliveryMode)
 360 {
 361         Uint32  addr = (Uint)gpMP_LocalAPIC + 0x300;
 362         Uint32  val;
 363
 364         // Hi
 365         val = (Uint)APICID << 24;
 366         Log("*%p = 0x%08x", addr+0x10, val);
 367         *(Uint32*)(addr+0x10) = val;
 368         // Low (and send)
 369         val = ((DeliveryMode & 7) << 8) | (Vector & 0xFF);
 370         Log("*%p = 0x%08x", addr, val);
 371         *(Uint32*)addr = val;
 372 }
 373 #endif
 374
 375 /**
 376  * \fn void Proc_Start()
 377  * \brief Start process scheduler
 378  */
 379 void Proc_Start()
 380 {
 381         // Start Interrupts (and hence scheduler)
 382         __asm__ __volatile__("sti");
 383 }
 384
 385 /**
 386  * \fn tThread *Proc_GetCurThread()
 387  * \brief Gets the current thread
 388  */
 389 tThread *Proc_GetCurThread()
 390 {
 391         #if USE_MP
 392         return gaCPUs[ gaAPIC_to_CPU[gpMP_LocalAPIC->ID.Val&0xFF] ].Current;
 393         #else
 394         return gCurrentThread;
 395         #endif
 396 }
 397
 398 /**
 399  * \fn void Proc_ChangeStack()
 400  * \brief Swaps the current stack for a new one (in the proper stack reigon)
 401  */
 402 void Proc_ChangeStack()
 403 {
 404         Uint    esp, ebp;
 405         Uint    tmpEbp, oldEsp;
 406         Uint    curBase, newBase;
 407
 408         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 409         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 410
 411         oldEsp = esp;
 412
 413         // Create new KStack
 414         newBase = MM_NewKStack();
 415         // Check for errors
 416         if(newBase == 0) {
 417                 Panic("What the?? Unable to allocate space for initial kernel stack");
 418                 return;
 419         }
 420
 421         curBase = (Uint)&Kernel_Stack_Top;
 422
 423         LOG("curBase = 0x%x, newBase = 0x%x", curBase, newBase);
 424
 425         // Get ESP as a used size
 426         esp = curBase - esp;
 427         LOG("memcpy( %p, %p, 0x%x )", (void*)(newBase - esp), (void*)(curBase - esp), esp );
 428         // Copy used stack
 429         memcpy( (void*)(newBase - esp), (void*)(curBase - esp), esp );
 430         // Get ESP as an offset in the new stack
 431         esp = newBase - esp;
 432         // Adjust EBP
 433         ebp = newBase - (curBase - ebp);
 434
 435         // Repair EBPs & Stack Addresses
 436         // Catches arguments also, but may trash stack-address-like values
 437         for(tmpEbp = esp; tmpEbp < newBase; tmpEbp += 4)
 438         {
 439                 if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < curBase)
 440                         *(Uint*)tmpEbp += newBase - curBase;
 441         }
 442
 443         Proc_GetCurThread()->KernelStack = newBase;
 444
 445         __asm__ __volatile__ ("mov %0, %%esp"::"r"(esp));
 446         __asm__ __volatile__ ("mov %0, %%ebp"::"r"(ebp));
 447 }
 448
 449 /**
 450  * \fn int Proc_Clone(Uint *Err, Uint Flags)
 451  * \brief Clone the current process
 452  */
 453 int Proc_Clone(Uint *Err, Uint Flags)
 454 {
 455         tThread *newThread;
 456         tThread *cur = Proc_GetCurThread();
 457         Uint    eip, esp, ebp;
 458
 459         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 460         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 461
 462         newThread = Threads_CloneTCB(Err, Flags);
 463         if(!newThread)  return -1;
 464
 465         // Initialise Memory Space (New Addr space or kernel stack)
 466         if(Flags & CLONE_VM) {
 467                 newThread->MemState.CR3 = MM_Clone();
 468                 newThread->KernelStack = cur->KernelStack;
 469         } else {
 470                 Uint    tmpEbp, oldEsp = esp;
 471
 472                 // Set CR3
 473                 newThread->MemState.CR3 = cur->MemState.CR3;
 474
 475                 // Create new KStack
 476                 newThread->KernelStack = MM_NewKStack();
 477                 // Check for errors
 478                 if(newThread->KernelStack == 0) {
 479                         free(newThread);
 480                         return -1;
 481                 }
 482
 483                 // Get ESP as a used size
 484                 esp = cur->KernelStack - esp;
 485                 // Copy used stack
 486                 memcpy( (void*)(newThread->KernelStack - esp), (void*)(cur->KernelStack - esp), esp );
 487                 // Get ESP as an offset in the new stack
 488                 esp = newThread->KernelStack - esp;
 489                 // Adjust EBP
 490                 ebp = newThread->KernelStack - (cur->KernelStack - ebp);
 491
 492                 // Repair EBPs & Stack Addresses
 493                 // Catches arguments also, but may trash stack-address-like values
 494                 for(tmpEbp = esp; tmpEbp < newThread->KernelStack; tmpEbp += 4)
 495                 {
 496                         if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < cur->KernelStack)
 497                                 *(Uint*)tmpEbp += newThread->KernelStack - cur->KernelStack;
 498                 }
 499         }
 500
 501         // Save core machine state
 502         newThread->SavedState.ESP = esp;
 503         newThread->SavedState.EBP = ebp;
 504         eip = GetEIP();
 505         if(eip == SWITCH_MAGIC) {
 506                 outb(0x20, 0x20);       // ACK Timer and return as child
 507                 return 0;
 508         }
 509
 510         // Set EIP as parent
 511         newThread->SavedState.EIP = eip;
 512
 513         // Lock list and add to active
 514         Threads_AddActive(newThread);
 515
 516         return newThread->TID;
 517 }
 518
 519 /**
 520  * \fn int Proc_SpawnWorker()
 521  * \brief Spawns a new worker thread
 522  */
 523 int Proc_SpawnWorker()
 524 {
 525         tThread *new, *cur;
 526         Uint    eip, esp, ebp;
 527
 528         cur = Proc_GetCurThread();
 529
 530         // Create new thread
 531         new = malloc( sizeof(tThread) );
 532         if(!new) {
 533                 Warning("Proc_SpawnWorker - Out of heap space!\n");
 534                 return -1;
 535         }
 536         memcpy(new, &gThreadZero, sizeof(tThread));
 537         // Set Thread ID
 538         new->TID = giNextTID++;
 539         // Create a new worker stack (in PID0's address space)
 540         // The stack is relocated by this code
 541         new->KernelStack = MM_NewWorkerStack();
 542
 543         // Get ESP and EBP based in the new stack
 544         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 545         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 546         esp = new->KernelStack - (cur->KernelStack - esp);
 547         ebp = new->KernelStack - (cur->KernelStack - ebp);
 548
 549         // Save core machine state
 550         new->SavedState.ESP = esp;
 551         new->SavedState.EBP = ebp;
 552         eip = GetEIP();
 553         if(eip == SWITCH_MAGIC) {
 554                 outb(0x20, 0x20);       // ACK Timer and return as child
 555                 return 0;
 556         }
 557
 558         // Set EIP as parent
 559         new->SavedState.EIP = eip;
 560         // Mark as active
 561         new->Status = THREAD_STAT_ACTIVE;
 562         Threads_AddActive( new );
 563
 564         return new->TID;
 565 }
 566
 567 /**
 568  * \fn Uint Proc_MakeUserStack()
 569  * \brief Creates a new user stack
 570  */
 571 Uint Proc_MakeUserStack()
 572 {
 573          int    i;
 574         Uint    base = USER_STACK_TOP - USER_STACK_SZ;
 575
 576         // Check Prospective Space
 577         for( i = USER_STACK_SZ >> 12; i--; )
 578                 if( MM_GetPhysAddr( base + (i<<12) ) != 0 )
 579                         break;
 580
 581         if(i != -1)     return 0;
 582
 583         // Allocate Stack - Allocate incrementally to clean up MM_Dump output
 584         for( i = 0; i < USER_STACK_SZ/4069; i++ )
 585                 MM_Allocate( base + (i<<12) );
 586
 587         return base + USER_STACK_SZ;
 588 }
 589
 590
 591 /**
 592  * \fn void Proc_StartUser(Uint Entrypoint, Uint *Bases, int ArgC, char **ArgV, char **EnvP, int DataSize)
 593  * \brief Starts a user task
 594  */
 595 void Proc_StartUser(Uint Entrypoint, Uint *Bases, int ArgC, char **ArgV, char **EnvP, int DataSize)
 596 {
 597         Uint    *stack = (void*)Proc_MakeUserStack();
 598          int    i;
 599         Uint    delta;
 600         Uint16  ss, cs;
 601
 602         LOG("stack = 0x%x", stack);
 603
 604         // Copy Arguments
 605         stack = (void*)( (Uint)stack - DataSize );
 606         memcpy( stack, ArgV, DataSize );
 607
 608         // Adjust Arguments and environment
 609         delta = (Uint)stack - (Uint)ArgV;
 610         ArgV = (char**)stack;
 611         for( i = 0; ArgV[i]; i++ )      ArgV[i] += delta;
 612         i ++;
 613         EnvP = &ArgV[i];
 614         for( i = 0; EnvP[i]; i++ )      EnvP[i] += delta;
 615
 616         // User Mode Segments
 617         ss = 0x23;      cs = 0x1B;
 618
 619         // Arguments
 620         *--stack = (Uint)EnvP;
 621         *--stack = (Uint)ArgV;
 622         *--stack = (Uint)ArgC;
 623         while(*Bases)
 624                 *--stack = *Bases++;
 625         *--stack = 0;   // Return Address
 626
 627         Proc_StartProcess(ss, (Uint)stack, 0x202, cs, Entrypoint);
 628 }
 629
 630 void Proc_StartProcess(Uint16 SS, Uint Stack, Uint Flags, Uint16 CS, Uint IP)
 631 {
 632         Uint    *stack = (void*)Stack;
 633         *--stack = SS;          //Stack Segment
 634         *--stack = Stack;       //Stack Pointer
 635         *--stack = Flags;       //EFLAGS (Resvd (0x2) and IF (0x20))
 636         *--stack = CS;          //Code Segment
 637         *--stack = IP;  //EIP
 638         //PUSHAD
 639         *--stack = 0xAAAAAAAA;  // eax
 640         *--stack = 0xCCCCCCCC;  // ecx
 641         *--stack = 0xDDDDDDDD;  // edx
 642         *--stack = 0xBBBBBBBB;  // ebx
 643         *--stack = 0xD1D1D1D1;  // edi
 644         *--stack = 0x54545454;  // esp - NOT POPED
 645         *--stack = 0x51515151;  // esi
 646         *--stack = 0xB4B4B4B4;  // ebp
 647         //Individual PUSHs
 648         *--stack = SS;  // ds
 649         *--stack = SS;  // es
 650         *--stack = SS;  // fs
 651         *--stack = SS;  // gs
 652
 653         __asm__ __volatile__ (
 654         "mov %%eax,%%esp;\n\t"  // Set stack pointer
 655         "pop %%gs;\n\t"
 656         "pop %%fs;\n\t"
 657         "pop %%es;\n\t"
 658         "pop %%ds;\n\t"
 659         "popa;\n\t"
 660         "iret;\n\t" : : "a" (stack));
 661         for(;;);
 662 }
 663
 664 /**
 665  * \fn int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 666  * \brief Demotes a process to a lower permission level
 667  * \param Err   Pointer to user's errno
 668  * \param Dest  New Permission Level
 669  * \param Regs  Pointer to user's register structure
 670  */
 671 int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 672 {
 673          int    cpl = Regs->cs & 3;
 674         // Sanity Check
 675         if(Dest > 3 || Dest < 0) {
 676                 *Err = -EINVAL;
 677                 return -1;
 678         }
 679
 680         // Permission Check
 681         if(cpl > Dest) {
 682                 *Err = -EACCES;
 683                 return -1;
 684         }
 685
 686         // Change the Segment Registers
 687         Regs->cs = (((Dest+1)<<4) | Dest) - 8;
 688         Regs->ss = ((Dest+1)<<4) | Dest;
 689         // Check if the GP Segs are GDT, then change them
 690         if(!(Regs->ds & 4))     Regs->ds = ((Dest+1)<<4) | Dest;
 691         if(!(Regs->es & 4))     Regs->es = ((Dest+1)<<4) | Dest;
 692         if(!(Regs->fs & 4))     Regs->fs = ((Dest+1)<<4) | Dest;
 693         if(!(Regs->gs & 4))     Regs->gs = ((Dest+1)<<4) | Dest;
 694
 695         return 0;
 696 }
 697
 698 /**
 699  * \brief Calls a signal handler in user mode
 700  * \note Used for signals
 701  */
 702 void Proc_CallFaultHandler(tThread *Thread)
 703 {
 704         // Rewinds the stack and calls the user function
 705         // Never returns
 706         __asm__ __volatile__ ("mov %0, %%ebp;\n\tcall Proc_AlterUserReturnAddr" :: "r"(Thread->FaultHandler));
 707         for(;;);
 708 }
 709
 710 /**
 711  * \fn void Proc_Scheduler(int CPU)
 712  * \brief Swap current thread and clears dead threads
 713  */
 714 void Proc_Scheduler(int CPU)
 715 {
 716         Uint    esp, ebp, eip;
 717         tThread *thread;
 718
 719         // If the spinlock is set, let it complete
 720         if(giThreadListLock)    return;
 721
 722         // Clear Delete Queue
 723         while(gDeleteThreads)
 724         {
 725                 thread = gDeleteThreads->Next;
 726                 if(gDeleteThreads->IsLocked) {  // Only free if structure is unused
 727                         gDeleteThreads->Status = THREAD_STAT_NULL;
 728                         free( gDeleteThreads );
 729                 }
 730                 gDeleteThreads = thread;
 731         }
 732
 733         // Check if there is any tasks running
 734         if(giNumActiveThreads == 0) {
 735                 Log("No Active threads, sleeping");
 736                 __asm__ __volatile__ ("hlt");
 737                 return;
 738         }
 739
 740         // Get current thread
 741         #if USE_MP
 742         thread = gaCPUs[CPU].Current;
 743         #else
 744         thread = gCurrentThread;
 745         #endif
 746
 747         // Reduce remaining quantum and continue timeslice if non-zero
 748         if(thread->Remaining--) return;
 749         // Reset quantum for next call
 750         thread->Remaining = thread->Quantum;
 751
 752         // Get machine state
 753         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 754         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 755         eip = GetEIP();
 756         if(eip == SWITCH_MAGIC) return; // Check if a switch happened
 757
 758         // Save machine state
 759         thread->SavedState.ESP = esp;
 760         thread->SavedState.EBP = ebp;
 761         thread->SavedState.EIP = eip;
 762
 763         // Get next thread
 764         thread = Threads_GetNextToRun(CPU);
 765
 766         // Error Check
 767         if(thread == NULL) {
 768                 Warning("Hmm... Threads_GetNextToRun returned NULL, I don't think this should happen.\n");
 769                 return;
 770         }
 771
 772         #if DEBUG_TRACE_SWITCH
 773         Log("Switching to task %i, CR3 = 0x%x, EIP = %p",
 774                 thread->TID,
 775                 thread->MemState.CR3,
 776                 thread->SavedState.EIP
 777                 );
 778         #endif
 779
 780         // Set current thread
 781         #if USE_MP
 782         gaCPUs[CPU].Current = thread;
 783         #else
 784         gCurrentThread = thread;
 785         #endif
 786
 787         // Update Kernel Stack pointer
 788         gTSSs[CPU].ESP0 = thread->KernelStack-4;
 789
 790         // Set address space
 791         #if USE_PAE
 792         # error "Todo: Implement PAE Address space switching"
 793         #else
 794                 __asm__ __volatile__ ("mov %0, %%cr3"::"a"(thread->MemState.CR3));
 795         #endif
 796
 797         #if 0
 798         if(thread->SavedState.ESP > 0xC0000000
 799         && thread->SavedState.ESP < thread->KernelStack-0x2000) {
 800                 Log_Warning("Proc", "Possible bad ESP %p (PID %i)", thread->SavedState.ESP);
 801         }
 802         #endif
 803
 804         // Switch threads
 805         __asm__ __volatile__ (
 806                 "mov %1, %%esp\n\t"     // Restore ESP
 807                 "mov %2, %%ebp\n\t"     // and EBP
 808                 "jmp *%3" : :   // And return to where we saved state (Proc_Clone or Proc_Scheduler)
 809                 "a"(SWITCH_MAGIC), "b"(thread->SavedState.ESP),
 810                 "d"(thread->SavedState.EBP), "c"(thread->SavedState.EIP)
 811                 );
 812         for(;;);        // Shouldn't reach here
 813 }
 814
 815 // === EXPORTS ===
 816 EXPORT(Proc_SpawnWorker);