Kernel/arch/x86/proc.c

   1 /*
   2  * AcessOS Microkernel Version
   3  * proc.c
   4  */
   5 #include <common.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 Uint     GetEIP();       // start.asm
  23 extern Uint32   gaInitPageDir[1024];    // start.asm
  24 extern void     Kernel_Stack_Top;
  25 extern volatile int     giThreadListLock;
  26 extern int      giNumCPUs;
  27 extern int      giNextTID;
  28 extern int      giTotalTickets;
  29 extern int      giNumActiveThreads;
  30 extern tThread  gThreadZero;
  31 extern tThread  *gActiveThreads;
  32 extern tThread  *gSleepingThreads;
  33 extern tThread  *gDeleteThreads;
  34 extern tThread  *Threads_GetNextToRun(int CPU);
  35 extern void     Threads_Dump();
  36
  37 // === PROTOTYPES ===
  38 void    ArchThreads_Init();
  39 tThread *Proc_GetCurThread();
  40 void    Proc_ChangeStack();
  41  int    Proc_Clone(Uint *Err, Uint Flags);
  42 void    Proc_Scheduler();
  43
  44 // === GLOBALS ===
  45 // --- Current State ---
  46 #if USE_MP
  47 tThread *gCurrentThread[MAX_CPUS] = {NULL};
  48 #else
  49 tThread *gCurrentThread = NULL;
  50 #endif
  51 // --- Multiprocessing ---
  52 #if USE_MP
  53 tMPInfo *gMPTable = NULL;
  54 #endif
  55 #if USE_PAE
  56 Uint32  *gPML4s[4] = NULL;
  57 #endif
  58 tTSS    *gTSSs = NULL;
  59 #if !USE_MP
  60 tTSS    gTSS0 = {0};
  61 #endif
  62
  63 // === CODE ===
  64 /**
  65  * \fn void ArchThreads_Init()
  66  * \brief Starts the process scheduler
  67  */
  68 void ArchThreads_Init()
  69 {
  70         Uint    pos = 0;
  71         #if USE_MP
  72         // -- Initialise Multiprocessing
  73         // Find MP Floating Table
  74         // - EBDA
  75         for(pos = KERNEL_BASE|0x9FC00; pos < (KERNEL_BASE|0xA0000); pos += 16) {
  76                 if( *(Uint*)(pos) == MPTABLE_IDENT ) {
  77                         if(ByteSum( (void*)pos, sizeof(tMPInfo) ) != 0) continue;
  78                         gMPTable = (void*)pos;
  79                         break;
  80                 }
  81         }
  82         // - Last KiB
  83         if(!gMPTable) {
  84
  85         }
  86         // - BIOS ROM
  87         if(!gMPTable) {
  88                 for(pos = KERNEL_BASE|0xF0000; pos < (KERNEL_BASE|0x100000); pos += 16) {
  89                         if( *(Uint*)(pos) == MPTABLE_IDENT ) {
  90                                 if(ByteSum( (void*)pos, sizeof(tMPInfo) ) != 0) continue;
  91                                 gMPTable = (void*)pos;
  92                                 break;
  93                         }
  94                 }
  95         }
  96
  97         // If the MP Table Exists, parse it
  98         if(gMPTable)
  99         {
 100                 Panic("Uh oh... MP Table Parsing is unimplemented\n");
 101         } else {
 102         #endif
 103                 giNumCPUs = 1;
 104                 gTSSs = &gTSS0;
 105         #if USE_MP
 106         }
 107
 108         // Initialise TSS
 109         for(pos=0;pos<giNumCPUs;pos++)
 110         {
 111         #else
 112         pos = 0;
 113         #endif
 114                 gTSSs[pos].SS0 = 0x10;
 115                 gTSSs[pos].ESP0 = 0;    // Set properly by scheduler
 116                 gGDT[5+pos].LimitLow = sizeof(tTSS);
 117                 gGDT[5+pos].LimitHi = 0;
 118                 gGDT[5+pos].Access = 0x89;      // Type
 119                 gGDT[5+pos].Flags = 0x4;
 120                 gGDT[5+pos].BaseLow = (Uint)&gTSSs[pos] & 0xFFFF;
 121                 gGDT[5+pos].BaseMid = (Uint)&gTSSs[pos] >> 16;
 122                 gGDT[5+pos].BaseHi = (Uint)&gTSSs[pos] >> 24;
 123         #if USE_MP
 124         }
 125         for(pos=0;pos<giNumCPUs;pos++) {
 126         #endif
 127                 __asm__ __volatile__ ("ltr %%ax"::"a"(0x28+pos*8));
 128         #if USE_MP
 129         }
 130         #endif
 131
 132         #if USE_MP
 133         gCurrentThread[0] = &gThreadZero;
 134         #else
 135         gCurrentThread = &gThreadZero;
 136         #endif
 137
 138         #if USE_PAE
 139         gThreadZero.MemState.PDP[0] = 0;
 140         gThreadZero.MemState.PDP[1] = 0;
 141         gThreadZero.MemState.PDP[2] = 0;
 142         #else
 143         gThreadZero.MemState.CR3 = (Uint)gaInitPageDir - KERNEL_BASE;
 144         #endif
 145
 146         // Set timer frequency
 147         outb(0x43, 0x34);       // Set Channel 0, Low/High, Rate Generator
 148         outb(0x40, TIMER_DIVISOR&0xFF); // Low Byte of Divisor
 149         outb(0x40, (TIMER_DIVISOR>>8)&0xFF);    // High Byte
 150
 151         // Create Per-Process Data Block
 152         MM_Allocate(MM_PPD_CFG);
 153
 154         // Change Stacks
 155         Proc_ChangeStack();
 156 }
 157
 158 /**
 159  * \fn void Proc_Start()
 160  * \brief Start process scheduler
 161  */
 162 void Proc_Start()
 163 {
 164         // Start Interrupts (and hence scheduler)
 165         __asm__ __volatile__("sti");
 166 }
 167
 168 /**
 169  * \fn tThread *Proc_GetCurThread()
 170  * \brief Gets the current thread
 171  */
 172 tThread *Proc_GetCurThread()
 173 {
 174         #if USE_MP
 175         return NULL;
 176         #else
 177         return gCurrentThread;
 178         #endif
 179 }
 180
 181 /**
 182  * \fn void Proc_ChangeStack()
 183  * \brief Swaps the current stack for a new one (in the proper stack reigon)
 184  */
 185 void Proc_ChangeStack()
 186 {
 187         Uint    esp, ebp;
 188         Uint    tmpEbp, oldEsp;
 189         Uint    curBase, newBase;
 190
 191         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 192         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 193
 194         oldEsp = esp;
 195
 196         // Create new KStack
 197         newBase = MM_NewKStack();
 198         // Check for errors
 199         if(newBase == 0) {
 200                 Panic("What the?? Unable to allocate space for initial kernel stack");
 201                 return;
 202         }
 203
 204         curBase = (Uint)&Kernel_Stack_Top;
 205
 206         LOG("curBase = 0x%x, newBase = 0x%x", curBase, newBase);
 207
 208         // Get ESP as a used size
 209         esp = curBase - esp;
 210         LOG("memcpy( %p, %p, 0x%x )", (void*)(newBase - esp), (void*)(curBase - esp), esp );
 211         // Copy used stack
 212         memcpy( (void*)(newBase - esp), (void*)(curBase - esp), esp );
 213         // Get ESP as an offset in the new stack
 214         esp = newBase - esp;
 215         // Adjust EBP
 216         ebp = newBase - (curBase - ebp);
 217
 218         // Repair EBPs & Stack Addresses
 219         // Catches arguments also, but may trash stack-address-like values
 220         for(tmpEbp = esp; tmpEbp < newBase; tmpEbp += 4)
 221         {
 222                 if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < curBase)
 223                         *(Uint*)tmpEbp += newBase - curBase;
 224         }
 225
 226         gCurrentThread->KernelStack = newBase;
 227
 228         __asm__ __volatile__ ("mov %0, %%esp"::"r"(esp));
 229         __asm__ __volatile__ ("mov %0, %%ebp"::"r"(ebp));
 230 }
 231
 232 /**
 233  * \fn int Proc_Clone(Uint *Err, Uint Flags)
 234  * \brief Clone the current process
 235  */
 236 int Proc_Clone(Uint *Err, Uint Flags)
 237 {
 238         tThread *newThread;
 239         tThread *cur = Proc_GetCurThread();
 240         Uint    eip, esp, ebp;
 241
 242         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 243         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 244
 245         // Create new thread structure
 246         newThread = malloc( sizeof(tThread) );
 247         if(!newThread) {
 248                 Warning("Proc_Clone - Out of memory when creating thread\n");
 249                 *Err = -ENOMEM;
 250                 return -1;
 251         }
 252
 253         // Base new thread on current
 254         memcpy(newThread, cur, sizeof(tThread));
 255
 256         // Initialise Memory Space (New Addr space or kernel stack)
 257         if(Flags & CLONE_VM) {
 258                 newThread->TGID = newThread->TID;
 259                 newThread->MemState.CR3 = MM_Clone();
 260         } else {
 261                 Uint    tmpEbp, oldEsp = esp;
 262
 263                 // Create new KStack
 264                 newThread->KernelStack = MM_NewKStack();
 265                 // Check for errors
 266                 if(newThread->KernelStack == 0) {
 267                         free(newThread);
 268                         return -1;
 269                 }
 270
 271                 // Get ESP as a used size
 272                 esp = cur->KernelStack - esp;
 273                 // Copy used stack
 274                 memcpy( (void*)(newThread->KernelStack - esp), (void*)(cur->KernelStack - esp), esp );
 275                 // Get ESP as an offset in the new stack
 276                 esp = newThread->KernelStack - esp;
 277                 // Adjust EBP
 278                 ebp = newThread->KernelStack - (cur->KernelStack - ebp);
 279
 280                 // Repair EBPs & Stack Addresses
 281                 // Catches arguments also, but may trash stack-address-like values
 282                 for(tmpEbp = esp; tmpEbp < newThread->KernelStack; tmpEbp += 4)
 283                 {
 284                         if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < cur->KernelStack)
 285                                 *(Uint*)tmpEbp += newThread->KernelStack - cur->KernelStack;
 286                 }
 287         }
 288
 289         // Set Pointer, Spinlock and TID
 290         newThread->Next = NULL;
 291         newThread->IsLocked = 0;
 292         newThread->TID = giNextTID++;
 293         newThread->PTID = cur->TID;
 294
 295         // Create copy of name
 296         newThread->ThreadName = malloc(strlen(cur->ThreadName)+1);
 297         strcpy(newThread->ThreadName, cur->ThreadName);
 298
 299         // Clear message list (messages are not inherited)
 300         newThread->Messages = NULL;
 301         newThread->LastMessage = NULL;
 302
 303         // Set remaining (sheduler expects remaining to be correct)
 304         newThread->Remaining = newThread->Quantum;
 305
 306         // Save core machine state
 307         newThread->SavedState.ESP = esp;
 308         newThread->SavedState.EBP = ebp;
 309         eip = GetEIP();
 310         if(eip == SWITCH_MAGIC) {
 311                 outb(0x20, 0x20);       // ACK Timer and return as child
 312                 return 0;
 313         }
 314
 315         // Set EIP as parent
 316         newThread->SavedState.EIP = eip;
 317
 318         // Lock list and add to active
 319         Threads_AddActive(newThread);
 320
 321         //Threads_Dump();
 322
 323         return newThread->TID;
 324 }
 325
 326 /**
 327  * \fn Uint Proc_MakeUserStack()
 328  * \brief Creates a new user stack
 329  */
 330 Uint Proc_MakeUserStack()
 331 {
 332          int    i;
 333         Uint    base = USER_STACK_TOP - USER_STACK_SZ;
 334
 335         // Check Prospective Space
 336         for( i = USER_STACK_SZ >> 12; i--; )
 337                 if( MM_GetPhysAddr( base + (i<<12) ) != 0 )
 338                         break;
 339
 340         if(i != -1)     return 0;
 341
 342         // Allocate Stack - Allocate incrementally to clean up MM_Dump output
 343         for( i = 0; i < USER_STACK_SZ/4069; i++ )
 344                 MM_Allocate( base + (i<<12) );
 345
 346         return base + USER_STACK_SZ;
 347 }
 348
 349
 350 /**
 351  * \fn void Proc_StartUser(Uint Entrypoint, Uint Base, int ArgC, char **ArgV, char **EnvP, int DataSize)
 352  * \brief Starts a user task
 353  */
 354 void Proc_StartUser(Uint Entrypoint, Uint *Bases, int ArgC, char **ArgV, char **EnvP, int DataSize)
 355 {
 356         Uint    *stack = (void*)Proc_MakeUserStack();
 357          int    i;
 358         Uint    delta;
 359         Uint16  ss, cs;
 360
 361         LOG("stack = 0x%x", stack);
 362
 363         // Copy Arguments
 364         stack = (void*)( (Uint)stack - DataSize );
 365         memcpy( stack, ArgV, DataSize );
 366
 367         // Adjust Arguments and environment
 368         delta = (Uint)stack - (Uint)ArgV;
 369         ArgV = (char**)stack;
 370         for( i = 0; ArgV[i]; i++ )      ArgV[i] += delta;
 371         i ++;
 372         EnvP = &ArgV[i];
 373         for( i = 0; EnvP[i]; i++ )      EnvP[i] += delta;
 374
 375         // User Mode Segments
 376         ss = 0x23;      cs = 0x1B;
 377
 378         // Arguments
 379         *--stack = (Uint)EnvP;
 380         *--stack = (Uint)ArgV;
 381         *--stack = (Uint)ArgC;
 382         while(*Bases)
 383                 *--stack = *Bases++;
 384         *--stack = 0;   // Return Address
 385         delta = (Uint)stack;    // Reuse delta to save SP
 386
 387         *--stack = ss;          //Stack Segment
 388         *--stack = delta;       //Stack Pointer
 389         *--stack = 0x0202;      //EFLAGS (Resvd (0x2) and IF (0x20))
 390         *--stack = cs;          //Code Segment
 391         *--stack = Entrypoint;  //EIP
 392         //PUSHAD
 393         *--stack = 0xAAAAAAAA;  // eax
 394         *--stack = 0xCCCCCCCC;  // ecx
 395         *--stack = 0xDDDDDDDD;  // edx
 396         *--stack = 0xBBBBBBBB;  // ebx
 397         *--stack = 0xD1D1D1D1;  // edi
 398         *--stack = 0x54545454;  // esp - NOT POPED
 399         *--stack = 0x51515151;  // esi
 400         *--stack = 0xB4B4B4B4;  // ebp
 401         //Individual PUSHs
 402         *--stack = ss;  // ds
 403         *--stack = ss;  // es
 404         *--stack = ss;  // fs
 405         *--stack = ss;  // gs
 406
 407         __asm__ __volatile__ (
 408         "mov %%eax,%%esp;\n\t"  // Set stack pointer
 409         "pop %%gs;\n\t"
 410         "pop %%fs;\n\t"
 411         "pop %%es;\n\t"
 412         "pop %%ds;\n\t"
 413         "popa;\n\t"
 414         "iret;\n\t" : : "a" (stack));
 415         for(;;);
 416 }
 417
 418 /**
 419  * \fn int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 420  * \brief Demotes a process to a lower permission level
 421  * \param Err   Pointer to user's errno
 422  */
 423 int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 424 {
 425          int    cpl = Regs->cs & 3;
 426         // Sanity Check
 427         if(Dest > 3 || Dest < 0) {
 428                 *Err = -EINVAL;
 429                 return -1;
 430         }
 431
 432         // Permission Check
 433         if(cpl > Dest) {
 434                 *Err = -EACCES;
 435                 return -1;
 436         }
 437
 438         // Change the Segment Registers
 439         Regs->cs = (((Dest+1)<<4) | Dest) - 8;
 440         Regs->ss = ((Dest+1)<<4) | Dest;
 441         // Check if the GP Segs are GDT, then change them
 442         if(!(Regs->ds & 4))     Regs->ds = ((Dest+1)<<4) | Dest;
 443         if(!(Regs->es & 4))     Regs->es = ((Dest+1)<<4) | Dest;
 444         if(!(Regs->fs & 4))     Regs->fs = ((Dest+1)<<4) | Dest;
 445         if(!(Regs->gs & 4))     Regs->gs = ((Dest+1)<<4) | Dest;
 446
 447         return 0;
 448 }
 449
 450 /**
 451  * \fn void Proc_Scheduler(int CPU)
 452  * \brief Swap current thread and clears dead threads
 453  */
 454 void Proc_Scheduler(int CPU)
 455 {
 456         Uint    esp, ebp, eip;
 457         tThread *thread;
 458
 459         // If the spinlock is set, let it complete
 460         if(giThreadListLock)    return;
 461
 462         // Clear Delete Queue
 463         while(gDeleteThreads)
 464         {
 465                 thread = gDeleteThreads->Next;
 466                 if(gDeleteThreads->IsLocked) {  // Only free if structure is unused
 467                         gDeleteThreads->Status = THREAD_STAT_NULL;
 468                         free( gDeleteThreads );
 469                 }
 470                 gDeleteThreads = thread;
 471         }
 472
 473         // Check if there is any tasks running
 474         if(giNumActiveThreads == 0) {
 475                 Log("No Active threads, sleeping");
 476                 __asm__ __volatile__ ("hlt");
 477                 return;
 478         }
 479
 480         // Reduce remaining quantum and continue timeslice if non-zero
 481         if(gCurrentThread->Remaining--) return;
 482         // Reset quantum for next call
 483         gCurrentThread->Remaining = gCurrentThread->Quantum;
 484
 485         // Get machine state
 486         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 487         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 488         eip = GetEIP();
 489         if(eip == SWITCH_MAGIC) return; // Check if a switch happened
 490
 491         // Save machine state
 492         gCurrentThread->SavedState.ESP = esp;
 493         gCurrentThread->SavedState.EBP = ebp;
 494         gCurrentThread->SavedState.EIP = eip;
 495
 496         // Get next thread
 497         thread = Threads_GetNextToRun(CPU);
 498
 499         // Error Check
 500         if(thread == NULL) {
 501                 Warning("Hmm... Threads_GetNextToRun returned NULL, I don't think this should happen.\n");
 502                 return;
 503         }
 504
 505         #if DEBUG_TRACE_SWITCH
 506         Log("Switching to task %i, CR3 = 0x%x, EIP = %p",
 507                 thread->TID,
 508                 thread->MemState.CR3,
 509                 thread->SavedState.EIP
 510                 );
 511         #endif
 512
 513         // Set current thread
 514         gCurrentThread = thread;
 515
 516         // Update Kernel Stack pointer
 517         gTSSs[CPU].ESP0 = thread->KernelStack;
 518
 519         // Set address space
 520         __asm__ __volatile__ ("mov %0, %%cr3"::"a"(gCurrentThread->MemState.CR3));
 521         // Switch threads
 522         __asm__ __volatile__ (
 523                 "mov %1, %%esp\n\t"
 524                 "mov %2, %%ebp\n\t"
 525                 "jmp *%3" : :
 526                 "a"(SWITCH_MAGIC), "b"(gCurrentThread->SavedState.ESP),
 527                 "d"(gCurrentThread->SavedState.EBP), "c"(gCurrentThread->SavedState.EIP));
 528         for(;;);        // Shouldn't reach here
 529 }