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         Uint    eip, esp, ebp;
 240
 241         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 242         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 243
 244         // Create new thread structure
 245         newThread = malloc( sizeof(tThread) );
 246         if(!newThread) {
 247                 Warning("Proc_Clone - Out of memory when creating thread\n");
 248                 *Err = -ENOMEM;
 249                 return -1;
 250         }
 251         // Base new thread on old
 252         memcpy(newThread, gCurrentThread, sizeof(tThread));
 253         // Initialise Memory Space (New Addr space or kernel stack)
 254         if(Flags & CLONE_VM) {
 255                 newThread->TGID = newThread->TID;
 256                 newThread->MemState.CR3 = MM_Clone();
 257         } else {
 258                 Uint    tmpEbp, oldEsp = esp;
 259
 260                 // Create new KStack
 261                 newThread->KernelStack = MM_NewKStack();
 262                 // Check for errors
 263                 if(newThread->KernelStack == 0) {
 264                         free(newThread);
 265                         return -1;
 266                 }
 267
 268                 // Get ESP as a used size
 269                 esp = gCurrentThread->KernelStack - esp;
 270                 // Copy used stack
 271                 memcpy( (void*)(newThread->KernelStack - esp), (void*)(gCurrentThread->KernelStack - esp), esp );
 272                 // Get ESP as an offset in the new stack
 273                 esp = newThread->KernelStack - esp;
 274                 // Adjust EBP
 275                 ebp = newThread->KernelStack - (gCurrentThread->KernelStack - ebp);
 276
 277                 // Repair EBPs & Stack Addresses
 278                 // Catches arguments also, but may trash stack-address-like values
 279                 for(tmpEbp = esp; tmpEbp < newThread->KernelStack; tmpEbp += 4)
 280                 {
 281                         if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < gCurrentThread->KernelStack)
 282                                 *(Uint*)tmpEbp += newThread->KernelStack - gCurrentThread->KernelStack;
 283                 }
 284         }
 285
 286         // Set Pointer, Spinlock and TID
 287         newThread->Next = NULL;
 288         newThread->IsLocked = 0;
 289         newThread->TID = giNextTID++;
 290         newThread->PTID = gCurrentThread->TID;
 291
 292         // Clear message list (messages are not inherited)
 293         newThread->Messages = NULL;
 294         newThread->LastMessage = NULL;
 295
 296         // Set remaining (sheduler expects remaining to be correct)
 297         newThread->Remaining = newThread->Quantum;
 298
 299         // Save core machine state
 300         newThread->SavedState.ESP = esp;
 301         newThread->SavedState.EBP = ebp;
 302         eip = GetEIP();
 303         if(eip == SWITCH_MAGIC) {
 304                 outb(0x20, 0x20);       // ACK Timer and return as child
 305                 return 0;
 306         }
 307
 308         // Set EIP as parent
 309         newThread->SavedState.EIP = eip;
 310
 311         // Lock list and add to active
 312         Threads_AddActive(newThread);
 313
 314         Threads_Dump();
 315
 316         return newThread->TID;
 317 }
 318
 319 /**
 320  * \fn Uint Proc_MakeUserStack()
 321  * \brief Creates a new user stack
 322  */
 323 Uint Proc_MakeUserStack()
 324 {
 325          int    i;
 326         Uint    base = USER_STACK_TOP - USER_STACK_SZ;
 327
 328         // Check Prospective Space
 329         for( i = USER_STACK_SZ >> 12; i--; )
 330                 if( MM_GetPhysAddr( base + (i<<12) ) != 0 )
 331                         break;
 332
 333         if(i != -1)     return 0;
 334
 335         // Allocate Stack - Allocate incrementally to clean up MM_Dump output
 336         for( i = 0; i < USER_STACK_SZ/4069; i++ )
 337                 MM_Allocate( base + (i<<12) );
 338
 339         return base + USER_STACK_SZ;
 340 }
 341
 342
 343 /**
 344  * \fn void Proc_StartUser(Uint Entrypoint, Uint Base, int ArgC, char **ArgV, char **EnvP, int DataSize)
 345  * \brief Starts a user task
 346  */
 347 void Proc_StartUser(Uint Entrypoint, Uint *Bases, int ArgC, char **ArgV, char **EnvP, int DataSize)
 348 {
 349         Uint    *stack = (void*)Proc_MakeUserStack();
 350          int    i;
 351         Uint    delta;
 352         Uint16  ss, cs;
 353
 354         LOG("stack = 0x%x", stack);
 355
 356         // Copy Arguments
 357         stack = (void*)( (Uint)stack - DataSize );
 358         memcpy( stack, ArgV, DataSize );
 359
 360         // Adjust Arguments and environment
 361         delta = (Uint)stack - (Uint)ArgV;
 362         ArgV = (char**)stack;
 363         for( i = 0; ArgV[i]; i++ )      ArgV[i] += delta;
 364         i ++;
 365         EnvP = &ArgV[i];
 366         for( i = 0; EnvP[i]; i++ )      EnvP[i] += delta;
 367
 368         // User Mode Segments
 369         ss = 0x23;      cs = 0x1B;
 370
 371         // Arguments
 372         *--stack = (Uint)EnvP;
 373         *--stack = (Uint)ArgV;
 374         *--stack = (Uint)ArgC;
 375         while(*Bases)
 376                 *--stack = *Bases++;
 377         *--stack = 0;   // Return Address
 378         delta = (Uint)stack;    // Reuse delta to save SP
 379
 380         *--stack = ss;          //Stack Segment
 381         *--stack = delta;       //Stack Pointer
 382         *--stack = 0x0202;      //EFLAGS (Resvd (0x2) and IF (0x20))
 383         *--stack = cs;          //Code Segment
 384         *--stack = Entrypoint;  //EIP
 385         //PUSHAD
 386         *--stack = 0xAAAAAAAA;  // eax
 387         *--stack = 0xCCCCCCCC;  // ecx
 388         *--stack = 0xDDDDDDDD;  // edx
 389         *--stack = 0xBBBBBBBB;  // ebx
 390         *--stack = 0xD1D1D1D1;  // edi
 391         *--stack = 0x54545454;  // esp - NOT POPED
 392         *--stack = 0x51515151;  // esi
 393         *--stack = 0xB4B4B4B4;  // ebp
 394         //Individual PUSHs
 395         *--stack = ss;  // ds
 396         *--stack = ss;  // es
 397         *--stack = ss;  // fs
 398         *--stack = ss;  // gs
 399
 400         __asm__ __volatile__ (
 401         "mov %%eax,%%esp;\n\t"  // Set stack pointer
 402         "pop %%gs;\n\t"
 403         "pop %%fs;\n\t"
 404         "pop %%es;\n\t"
 405         "pop %%ds;\n\t"
 406         "popa;\n\t"
 407         "iret;\n\t" : : "a" (stack));
 408         for(;;);
 409 }
 410
 411 /**
 412  * \fn int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 413  * \brief Demotes a process to a lower permission level
 414  * \param Err   Pointer to user's errno
 415  */
 416 int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 417 {
 418          int    cpl = Regs->cs & 3;
 419         // Sanity Check
 420         if(Dest > 3 || Dest < 0) {
 421                 *Err = -EINVAL;
 422                 return -1;
 423         }
 424
 425         // Permission Check
 426         if(cpl > Dest) {
 427                 *Err = -EACCES;
 428                 return -1;
 429         }
 430
 431         // Change the Segment Registers
 432         Regs->cs = (((Dest+1)<<4) | Dest) - 8;
 433         Regs->ss = ((Dest+1)<<4) | Dest;
 434         // Check if the GP Segs are GDT, then change them
 435         if(!(Regs->ds & 4))     Regs->ds = ((Dest+1)<<4) | Dest;
 436         if(!(Regs->es & 4))     Regs->es = ((Dest+1)<<4) | Dest;
 437         if(!(Regs->fs & 4))     Regs->fs = ((Dest+1)<<4) | Dest;
 438         if(!(Regs->gs & 4))     Regs->gs = ((Dest+1)<<4) | Dest;
 439
 440         return 0;
 441 }
 442
 443 /**
 444  * \fn void Proc_Scheduler(int CPU)
 445  * \brief Swap current thread and clears dead threads
 446  */
 447 void Proc_Scheduler(int CPU)
 448 {
 449         Uint    esp, ebp, eip;
 450         tThread *thread;
 451
 452         // If the spinlock is set, let it complete
 453         if(giThreadListLock)    return;
 454
 455         // Clear Delete Queue
 456         while(gDeleteThreads)
 457         {
 458                 thread = gDeleteThreads->Next;
 459                 if(gDeleteThreads->IsLocked) {  // Only free if structure is unused
 460                         gDeleteThreads->Status = THREAD_STAT_NULL;
 461                         free( gDeleteThreads );
 462                 }
 463                 gDeleteThreads = thread;
 464         }
 465
 466         // Check if there is any tasks running
 467         if(giNumActiveThreads == 0) {
 468                 Log("No Active threads, sleeping");
 469                 __asm__ __volatile__ ("hlt");
 470                 return;
 471         }
 472
 473         // Reduce remaining quantum and continue timeslice if non-zero
 474         if(gCurrentThread->Remaining--) return;
 475         // Reset quantum for next call
 476         gCurrentThread->Remaining = gCurrentThread->Quantum;
 477
 478         // Get machine state
 479         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 480         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 481         eip = GetEIP();
 482         if(eip == SWITCH_MAGIC) return; // Check if a switch happened
 483
 484         // Save machine state
 485         gCurrentThread->SavedState.ESP = esp;
 486         gCurrentThread->SavedState.EBP = ebp;
 487         gCurrentThread->SavedState.EIP = eip;
 488
 489         // Get next thread
 490         thread = Threads_GetNextToRun(CPU);
 491
 492         // Error Check
 493         if(thread == NULL) {
 494                 Warning("Hmm... Threads_GetNextToRun returned NULL, I don't think this should happen.\n");
 495                 return;
 496         }
 497
 498         #if DEBUG_TRACE_SWITCH
 499         Log("Switching to task %i, CR3 = 0x%x, EIP = %p",
 500                 thread->TID,
 501                 thread->MemState.CR3,
 502                 thread->SavedState.EIP
 503                 );
 504         #endif
 505
 506         // Set current thread
 507         gCurrentThread = thread;
 508
 509         // Update Kernel Stack pointer
 510         gTSSs[CPU].ESP0 = thread->KernelStack;
 511
 512         // Set address space
 513         __asm__ __volatile__ ("mov %0, %%cr3"::"a"(gCurrentThread->MemState.CR3));
 514         // Switch threads
 515         __asm__ __volatile__ (
 516                 "mov %1, %%esp\n\t"
 517                 "mov %2, %%ebp\n\t"
 518                 "jmp *%3" : :
 519                 "a"(SWITCH_MAGIC), "b"(gCurrentThread->SavedState.ESP),
 520                 "d"(gCurrentThread->SavedState.EBP), "c"(gCurrentThread->SavedState.EIP));
 521         for(;;);        // Shouldn't reach here
 522 }