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 tAPIC   *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
 180                                 if( !(ents->Proc.CPUFlags & 1) ) {
 181                                         Log("DISABLED");
 182                                         break;
 183                                 }
 184
 185                                 // Check if there is too many processors
 186                                 if(giNumCPUs >= MAX_CPUS) {
 187                                         giNumCPUs ++;   // If `giNumCPUs` > MAX_CPUS later, it will be clipped
 188                                         break;
 189                                 }
 190
 191                                 // Initialise CPU Info
 192                                 gaAPIC_to_CPU[ents->Proc.APICID] = giNumCPUs;
 193                                 gaCPUs[giNumCPUs].APICID = ents->Proc.APICID;
 194                                 gaCPUs[giNumCPUs].State = 0;
 195                                 giNumCPUs ++;
 196
 197                                 // Send IPI
 198                                 if( !(ents->Proc.CPUFlags & 2) )
 199                                 {
 200                                         MP_StartAP( giNumCPUs-1 );
 201                                 }
 202
 203                                 break;
 204                         case 1: // Bus
 205                                 entSize = 8;
 206                                 Log("%i: Bus", i);
 207                                 Log("\t.ID = %i", ents->Bus.ID);
 208                                 Log("\t.TypeString = '%6c'", ents->Bus.TypeString);
 209                                 break;
 210                         case 2: // I/O APIC
 211                                 entSize = 8;
 212                                 Log("%i: I/O APIC", i);
 213                                 Log("\t.ID = %i", ents->IOAPIC.ID);
 214                                 Log("\t.Version = 0x%02x", ents->IOAPIC.Version);
 215                                 Log("\t.Flags = 0x%02x", ents->IOAPIC.Flags);
 216                                 Log("\t.Addr = 0x%08x", ents->IOAPIC.Addr);
 217                                 break;
 218                         case 3: // I/O Interrupt Assignment
 219                                 entSize = 8;
 220                                 Log("%i: I/O Interrupt Assignment", i);
 221                                 Log("\t.IntType = %i", ents->IOInt.IntType);
 222                                 Log("\t.Flags = 0x%04x", ents->IOInt.Flags);
 223                                 Log("\t.SourceBusID = 0x%02x", ents->IOInt.SourceBusID);
 224                                 Log("\t.SourceBusIRQ = 0x%02x", ents->IOInt.SourceBusIRQ);
 225                                 Log("\t.DestAPICID = 0x%02x", ents->IOInt.DestAPICID);
 226                                 Log("\t.DestAPICIRQ = 0x%02x", ents->IOInt.DestAPICIRQ);
 227                                 break;
 228                         case 4: // Local Interrupt Assignment
 229                                 entSize = 8;
 230                                 Log("%i: Local Interrupt Assignment", i);
 231                                 Log("\t.IntType = %i", ents->LocalInt.IntType);
 232                                 Log("\t.Flags = 0x%04x", ents->LocalInt.Flags);
 233                                 Log("\t.SourceBusID = 0x%02x", ents->LocalInt.SourceBusID);
 234                                 Log("\t.SourceBusIRQ = 0x%02x", ents->LocalInt.SourceBusIRQ);
 235                                 Log("\t.DestLocalAPICID = 0x%02x", ents->LocalInt.DestLocalAPICID);
 236                                 Log("\t.DestLocalAPICIRQ = 0x%02x", ents->LocalInt.DestLocalAPICIRQ);
 237                                 break;
 238                         default:
 239                                 Log("%i: Unknown (%i)", i, ents->Type);
 240                                 break;
 241                         }
 242                         ents = (void*)( (Uint)ents + entSize );
 243                 }
 244
 245                 if( giNumCPUs > MAX_CPUS ) {
 246                         Warning("Too many CPUs detected (%i), only using %i of them", giNumCPUs, MAX_CPUS);
 247                 }
 248
 249                 Panic("Uh oh... MP Table Parsing is unimplemented\n");
 250         }
 251         else {
 252                 Log("No MP Table was found, assuming uniprocessor\n");
 253                 giNumCPUs = 1;
 254                 gTSSs = &gTSS0;
 255         }
 256         #else
 257         giNumCPUs = 1;
 258         gTSSs = &gTSS0;
 259         #endif
 260
 261         // Initialise Double Fault TSS
 262         /*
 263         gGDT[5].LimitLow = sizeof(tTSS);
 264         gGDT[5].LimitHi = 0;
 265         gGDT[5].Access = 0x89;  // Type
 266         gGDT[5].Flags = 0x4;
 267         */
 268         gGDT[5].BaseLow = (Uint)&gDoubleFault_TSS & 0xFFFF;
 269         gGDT[5].BaseMid = (Uint)&gDoubleFault_TSS >> 16;
 270         gGDT[5].BaseHi = (Uint)&gDoubleFault_TSS >> 24;
 271
 272         #if USE_MP
 273         // Initialise Normal TSS(s)
 274         for(pos=0;pos<giNumCPUs;pos++)
 275         {
 276         #else
 277         pos = 0;
 278         #endif
 279                 gTSSs[pos].SS0 = 0x10;
 280                 gTSSs[pos].ESP0 = 0;    // Set properly by scheduler
 281                 gGDT[6+pos].BaseLow = ((Uint)(&gTSSs[pos])) & 0xFFFF;
 282                 gGDT[6+pos].BaseMid = ((Uint)(&gTSSs[pos])) >> 16;
 283                 gGDT[6+pos].BaseHi = ((Uint)(&gTSSs[pos])) >> 24;
 284         #if USE_MP
 285         }
 286         for(pos=0;pos<giNumCPUs;pos++) {
 287         #endif
 288                 __asm__ __volatile__ ("ltr %%ax"::"a"(0x30+pos*8));
 289         #if USE_MP
 290         }
 291         #endif
 292
 293         #if USE_MP
 294         gaCPUs[0].Current = &gThreadZero;
 295         #else
 296         gCurrentThread = &gThreadZero;
 297         #endif
 298
 299         #if USE_PAE
 300         gThreadZero.MemState.PDP[0] = 0;
 301         gThreadZero.MemState.PDP[1] = 0;
 302         gThreadZero.MemState.PDP[2] = 0;
 303         #else
 304         gThreadZero.MemState.CR3 = (Uint)gaInitPageDir - KERNEL_BASE;
 305         #endif
 306
 307         // Set timer frequency
 308         outb(0x43, 0x34);       // Set Channel 0, Low/High, Rate Generator
 309         outb(0x40, TIMER_DIVISOR&0xFF); // Low Byte of Divisor
 310         outb(0x40, (TIMER_DIVISOR>>8)&0xFF);    // High Byte
 311
 312         // Create Per-Process Data Block
 313         MM_Allocate(MM_PPD_CFG);
 314
 315         // Change Stacks
 316         Proc_ChangeStack();
 317 }
 318
 319 #if USE_MP
 320 void MP_StartAP(int CPU)
 321 {
 322         Log("Starting AP %i (APIC %i)", CPU, gaCPUs[CPU].APICID);
 323         // Set location of AP startup code and mark for a warm restart
 324         *(Uint16*)(KERNEL_BASE|0x467) = (Uint)&APStartup - (KERNEL_BASE|0xFFFF0);
 325         *(Uint16*)(KERNEL_BASE|0x469) = 0xFFFF;
 326         outb(0x70, 0x0F);       outb(0x71, 0x0A);       // Warm Reset
 327         MP_SendIPI(gaCPUs[CPU].APICID, 0, 5);
 328 }
 329
 330 void MP_SendIPI(Uint8 APICID, int Vector, int DeliveryMode)
 331 {
 332         Uint32  addr = (Uint)gpMP_LocalAPIC + 0x300;
 333         Uint32  val;
 334
 335         // Hi
 336         val = (Uint)APICID << 24;
 337         Log("*%p = 0x%08x", addr+0x10, val);
 338         *(Uint32*)(addr+0x10) = val;
 339         // Low (and send)
 340         val = ((DeliveryMode & 7) << 8) | (Vector & 0xFF);
 341         Log("*%p = 0x%08x", addr, val);
 342         *(Uint32*)addr = val;
 343 }
 344 #endif
 345
 346 /**
 347  * \fn void Proc_Start()
 348  * \brief Start process scheduler
 349  */
 350 void Proc_Start()
 351 {
 352         // Start Interrupts (and hence scheduler)
 353         __asm__ __volatile__("sti");
 354 }
 355
 356 /**
 357  * \fn tThread *Proc_GetCurThread()
 358  * \brief Gets the current thread
 359  */
 360 tThread *Proc_GetCurThread()
 361 {
 362         #if USE_MP
 363         return gaCPUs[ gaAPIC_to_CPU[gpMP_LocalAPIC->ID.Val&0xFF] ].Current;
 364         #else
 365         return gCurrentThread;
 366         #endif
 367 }
 368
 369 /**
 370  * \fn void Proc_ChangeStack()
 371  * \brief Swaps the current stack for a new one (in the proper stack reigon)
 372  */
 373 void Proc_ChangeStack()
 374 {
 375         Uint    esp, ebp;
 376         Uint    tmpEbp, oldEsp;
 377         Uint    curBase, newBase;
 378
 379         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 380         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 381
 382         oldEsp = esp;
 383
 384         // Create new KStack
 385         newBase = MM_NewKStack();
 386         // Check for errors
 387         if(newBase == 0) {
 388                 Panic("What the?? Unable to allocate space for initial kernel stack");
 389                 return;
 390         }
 391
 392         curBase = (Uint)&Kernel_Stack_Top;
 393
 394         LOG("curBase = 0x%x, newBase = 0x%x", curBase, newBase);
 395
 396         // Get ESP as a used size
 397         esp = curBase - esp;
 398         LOG("memcpy( %p, %p, 0x%x )", (void*)(newBase - esp), (void*)(curBase - esp), esp );
 399         // Copy used stack
 400         memcpy( (void*)(newBase - esp), (void*)(curBase - esp), esp );
 401         // Get ESP as an offset in the new stack
 402         esp = newBase - esp;
 403         // Adjust EBP
 404         ebp = newBase - (curBase - ebp);
 405
 406         // Repair EBPs & Stack Addresses
 407         // Catches arguments also, but may trash stack-address-like values
 408         for(tmpEbp = esp; tmpEbp < newBase; tmpEbp += 4)
 409         {
 410                 if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < curBase)
 411                         *(Uint*)tmpEbp += newBase - curBase;
 412         }
 413
 414         Proc_GetCurThread()->KernelStack = newBase;
 415
 416         __asm__ __volatile__ ("mov %0, %%esp"::"r"(esp));
 417         __asm__ __volatile__ ("mov %0, %%ebp"::"r"(ebp));
 418 }
 419
 420 /**
 421  * \fn int Proc_Clone(Uint *Err, Uint Flags)
 422  * \brief Clone the current process
 423  */
 424 int Proc_Clone(Uint *Err, Uint Flags)
 425 {
 426         tThread *newThread;
 427         tThread *cur = Proc_GetCurThread();
 428         Uint    eip, esp, ebp;
 429
 430         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 431         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 432
 433         newThread = Threads_CloneTCB(Err, Flags);
 434         if(!newThread)  return -1;
 435
 436         // Initialise Memory Space (New Addr space or kernel stack)
 437         if(Flags & CLONE_VM) {
 438                 newThread->MemState.CR3 = MM_Clone();
 439                 newThread->KernelStack = cur->KernelStack;
 440         } else {
 441                 Uint    tmpEbp, oldEsp = esp;
 442
 443                 // Set CR3
 444                 newThread->MemState.CR3 = cur->MemState.CR3;
 445
 446                 // Create new KStack
 447                 newThread->KernelStack = MM_NewKStack();
 448                 // Check for errors
 449                 if(newThread->KernelStack == 0) {
 450                         free(newThread);
 451                         return -1;
 452                 }
 453
 454                 // Get ESP as a used size
 455                 esp = cur->KernelStack - esp;
 456                 // Copy used stack
 457                 memcpy( (void*)(newThread->KernelStack - esp), (void*)(cur->KernelStack - esp), esp );
 458                 // Get ESP as an offset in the new stack
 459                 esp = newThread->KernelStack - esp;
 460                 // Adjust EBP
 461                 ebp = newThread->KernelStack - (cur->KernelStack - ebp);
 462
 463                 // Repair EBPs & Stack Addresses
 464                 // Catches arguments also, but may trash stack-address-like values
 465                 for(tmpEbp = esp; tmpEbp < newThread->KernelStack; tmpEbp += 4)
 466                 {
 467                         if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < cur->KernelStack)
 468                                 *(Uint*)tmpEbp += newThread->KernelStack - cur->KernelStack;
 469                 }
 470         }
 471
 472         // Save core machine state
 473         newThread->SavedState.ESP = esp;
 474         newThread->SavedState.EBP = ebp;
 475         eip = GetEIP();
 476         if(eip == SWITCH_MAGIC) {
 477                 outb(0x20, 0x20);       // ACK Timer and return as child
 478                 return 0;
 479         }
 480
 481         // Set EIP as parent
 482         newThread->SavedState.EIP = eip;
 483
 484         // Lock list and add to active
 485         Threads_AddActive(newThread);
 486
 487         return newThread->TID;
 488 }
 489
 490 /**
 491  * \fn int Proc_SpawnWorker()
 492  * \brief Spawns a new worker thread
 493  */
 494 int Proc_SpawnWorker()
 495 {
 496         tThread *new, *cur;
 497         Uint    eip, esp, ebp;
 498
 499         cur = Proc_GetCurThread();
 500
 501         // Create new thread
 502         new = malloc( sizeof(tThread) );
 503         if(!new) {
 504                 Warning("Proc_SpawnWorker - Out of heap space!\n");
 505                 return -1;
 506         }
 507         memcpy(new, &gThreadZero, sizeof(tThread));
 508         // Set Thread ID
 509         new->TID = giNextTID++;
 510         // Create a new worker stack (in PID0's address space)
 511         // The stack is relocated by this code
 512         new->KernelStack = MM_NewWorkerStack();
 513
 514         // Get ESP and EBP based in the new stack
 515         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 516         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 517         esp = new->KernelStack - (cur->KernelStack - esp);
 518         ebp = new->KernelStack - (cur->KernelStack - ebp);
 519
 520         // Save core machine state
 521         new->SavedState.ESP = esp;
 522         new->SavedState.EBP = ebp;
 523         eip = GetEIP();
 524         if(eip == SWITCH_MAGIC) {
 525                 outb(0x20, 0x20);       // ACK Timer and return as child
 526                 return 0;
 527         }
 528
 529         // Set EIP as parent
 530         new->SavedState.EIP = eip;
 531         // Mark as active
 532         new->Status = THREAD_STAT_ACTIVE;
 533         Threads_AddActive( new );
 534
 535         return new->TID;
 536 }
 537
 538 /**
 539  * \fn Uint Proc_MakeUserStack()
 540  * \brief Creates a new user stack
 541  */
 542 Uint Proc_MakeUserStack()
 543 {
 544          int    i;
 545         Uint    base = USER_STACK_TOP - USER_STACK_SZ;
 546
 547         // Check Prospective Space
 548         for( i = USER_STACK_SZ >> 12; i--; )
 549                 if( MM_GetPhysAddr( base + (i<<12) ) != 0 )
 550                         break;
 551
 552         if(i != -1)     return 0;
 553
 554         // Allocate Stack - Allocate incrementally to clean up MM_Dump output
 555         for( i = 0; i < USER_STACK_SZ/4069; i++ )
 556                 MM_Allocate( base + (i<<12) );
 557
 558         return base + USER_STACK_SZ;
 559 }
 560
 561
 562 /**
 563  * \fn void Proc_StartUser(Uint Entrypoint, Uint *Bases, int ArgC, char **ArgV, char **EnvP, int DataSize)
 564  * \brief Starts a user task
 565  */
 566 void Proc_StartUser(Uint Entrypoint, Uint *Bases, int ArgC, char **ArgV, char **EnvP, int DataSize)
 567 {
 568         Uint    *stack = (void*)Proc_MakeUserStack();
 569          int    i;
 570         Uint    delta;
 571         Uint16  ss, cs;
 572
 573         LOG("stack = 0x%x", stack);
 574
 575         // Copy Arguments
 576         stack = (void*)( (Uint)stack - DataSize );
 577         memcpy( stack, ArgV, DataSize );
 578
 579         // Adjust Arguments and environment
 580         delta = (Uint)stack - (Uint)ArgV;
 581         ArgV = (char**)stack;
 582         for( i = 0; ArgV[i]; i++ )      ArgV[i] += delta;
 583         i ++;
 584         EnvP = &ArgV[i];
 585         for( i = 0; EnvP[i]; i++ )      EnvP[i] += delta;
 586
 587         // User Mode Segments
 588         ss = 0x23;      cs = 0x1B;
 589
 590         // Arguments
 591         *--stack = (Uint)EnvP;
 592         *--stack = (Uint)ArgV;
 593         *--stack = (Uint)ArgC;
 594         while(*Bases)
 595                 *--stack = *Bases++;
 596         *--stack = 0;   // Return Address
 597         delta = (Uint)stack;    // Reuse delta to save SP
 598
 599         *--stack = ss;          //Stack Segment
 600         *--stack = delta;       //Stack Pointer
 601         *--stack = 0x0202;      //EFLAGS (Resvd (0x2) and IF (0x20))
 602         *--stack = cs;          //Code Segment
 603         *--stack = Entrypoint;  //EIP
 604         //PUSHAD
 605         *--stack = 0xAAAAAAAA;  // eax
 606         *--stack = 0xCCCCCCCC;  // ecx
 607         *--stack = 0xDDDDDDDD;  // edx
 608         *--stack = 0xBBBBBBBB;  // ebx
 609         *--stack = 0xD1D1D1D1;  // edi
 610         *--stack = 0x54545454;  // esp - NOT POPED
 611         *--stack = 0x51515151;  // esi
 612         *--stack = 0xB4B4B4B4;  // ebp
 613         //Individual PUSHs
 614         *--stack = ss;  // ds
 615         *--stack = ss;  // es
 616         *--stack = ss;  // fs
 617         *--stack = ss;  // gs
 618
 619         __asm__ __volatile__ (
 620         "mov %%eax,%%esp;\n\t"  // Set stack pointer
 621         "pop %%gs;\n\t"
 622         "pop %%fs;\n\t"
 623         "pop %%es;\n\t"
 624         "pop %%ds;\n\t"
 625         "popa;\n\t"
 626         "iret;\n\t" : : "a" (stack));
 627         for(;;);
 628 }
 629
 630 /**
 631  * \fn int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 632  * \brief Demotes a process to a lower permission level
 633  * \param Err   Pointer to user's errno
 634  * \param Dest  New Permission Level
 635  * \param Regs  Pointer to user's register structure
 636  */
 637 int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 638 {
 639          int    cpl = Regs->cs & 3;
 640         // Sanity Check
 641         if(Dest > 3 || Dest < 0) {
 642                 *Err = -EINVAL;
 643                 return -1;
 644         }
 645
 646         // Permission Check
 647         if(cpl > Dest) {
 648                 *Err = -EACCES;
 649                 return -1;
 650         }
 651
 652         // Change the Segment Registers
 653         Regs->cs = (((Dest+1)<<4) | Dest) - 8;
 654         Regs->ss = ((Dest+1)<<4) | Dest;
 655         // Check if the GP Segs are GDT, then change them
 656         if(!(Regs->ds & 4))     Regs->ds = ((Dest+1)<<4) | Dest;
 657         if(!(Regs->es & 4))     Regs->es = ((Dest+1)<<4) | Dest;
 658         if(!(Regs->fs & 4))     Regs->fs = ((Dest+1)<<4) | Dest;
 659         if(!(Regs->gs & 4))     Regs->gs = ((Dest+1)<<4) | Dest;
 660
 661         return 0;
 662 }
 663
 664 /**
 665  * \fn void Proc_Scheduler(int CPU)
 666  * \brief Swap current thread and clears dead threads
 667  */
 668 void Proc_Scheduler(int CPU)
 669 {
 670         Uint    esp, ebp, eip;
 671         tThread *thread;
 672
 673         // If the spinlock is set, let it complete
 674         if(giThreadListLock)    return;
 675
 676         // Clear Delete Queue
 677         while(gDeleteThreads)
 678         {
 679                 thread = gDeleteThreads->Next;
 680                 if(gDeleteThreads->IsLocked) {  // Only free if structure is unused
 681                         gDeleteThreads->Status = THREAD_STAT_NULL;
 682                         free( gDeleteThreads );
 683                 }
 684                 gDeleteThreads = thread;
 685         }
 686
 687         // Check if there is any tasks running
 688         if(giNumActiveThreads == 0) {
 689                 Log("No Active threads, sleeping");
 690                 __asm__ __volatile__ ("hlt");
 691                 return;
 692         }
 693
 694         // Get current thread
 695         #if USE_MP
 696         thread = gaCPUs[CPU].Current;
 697         #else
 698         thread = gCurrentThread;
 699         #endif
 700
 701         // Reduce remaining quantum and continue timeslice if non-zero
 702         if(thread->Remaining--) return;
 703         // Reset quantum for next call
 704         thread->Remaining = thread->Quantum;
 705
 706         // Get machine state
 707         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 708         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 709         eip = GetEIP();
 710         if(eip == SWITCH_MAGIC) return; // Check if a switch happened
 711
 712         // Save machine state
 713         thread->SavedState.ESP = esp;
 714         thread->SavedState.EBP = ebp;
 715         thread->SavedState.EIP = eip;
 716
 717         // Get next thread
 718         thread = Threads_GetNextToRun(CPU);
 719
 720         // Error Check
 721         if(thread == NULL) {
 722                 Warning("Hmm... Threads_GetNextToRun returned NULL, I don't think this should happen.\n");
 723                 return;
 724         }
 725
 726         #if DEBUG_TRACE_SWITCH
 727         Log("Switching to task %i, CR3 = 0x%x, EIP = %p",
 728                 thread->TID,
 729                 thread->MemState.CR3,
 730                 thread->SavedState.EIP
 731                 );
 732         #endif
 733
 734         // Set current thread
 735         #if USE_MP
 736         gaCPUs[CPU].Current = thread;
 737         #else
 738         gCurrentThread = thread;
 739         #endif
 740
 741         // Update Kernel Stack pointer
 742         gTSSs[CPU].ESP0 = thread->KernelStack;
 743
 744         // Set address space
 745         #if USE_PAE
 746         # error "Todo: Implement PAE Address space switching"
 747         #else
 748                 __asm__ __volatile__ ("mov %0, %%cr3"::"a"(thread->MemState.CR3));
 749         #endif
 750         // Switch threads
 751         __asm__ __volatile__ (
 752                 "mov %1, %%esp\n\t"     // Restore ESP
 753                 "mov %2, %%ebp\n\t"     // and EBP
 754                 "jmp *%3" : :   // And return to where we saved state (Proc_Clone or Proc_Scheduler)
 755                 "a"(SWITCH_MAGIC), "b"(thread->SavedState.ESP),
 756                 "d"(thread->SavedState.EBP), "c"(thread->SavedState.EIP)
 757                 );
 758         for(;;);        // Shouldn't reach here
 759 }
 760
 761 // === EXPORTS ===
 762 EXPORT(Proc_SpawnWorker);