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 // === CONSTANTS ===
  14 #define SWITCH_MAGIC    0xFFFACE55      // There is no code in this area
  15 #define TIMER_DIVISOR   11931   //~100Hz
  16
  17 // === IMPORTS ===
  18 extern tGDT     gGDT[];
  19 extern Uint     GetEIP();       // start.asm
  20 extern Uint32   gaInitPageDir[1024];    // start.asm
  21 extern void     Kernel_Stack_Top;
  22 extern volatile int     giThreadListLock;
  23 extern int      giNumCPUs;
  24 extern int      giNextTID;
  25 extern int      giTotalTickets;
  26 extern int      giNumActiveThreads;
  27 extern tThread  gThreadZero;
  28 extern tThread  *gActiveThreads;
  29 extern tThread  *gSleepingThreads;
  30 extern tThread  *gDeleteThreads;
  31 extern tThread  *Threads_GetNextToRun(int CPU);
  32 extern void     Threads_Dump();
  33
  34 // === PROTOTYPES ===
  35 void    ArchThreads_Init();
  36 tThread *Proc_GetCurThread();
  37 void    Proc_ChangeStack();
  38  int    Proc_Clone(Uint *Err, Uint Flags);
  39 void    Proc_Scheduler();
  40
  41 // === GLOBALS ===
  42 // --- Current State ---
  43 #if USE_MP
  44 tThread *gCurrentThread[MAX_CPUS] = {NULL};
  45 #else
  46 tThread *gCurrentThread = NULL;
  47 #endif
  48 // --- Multiprocessing ---
  49 #if USE_MP
  50 tMPInfo *gMPTable = NULL;
  51 #endif
  52 #if USE_PAE
  53 Uint32  *gPML4s[4] = NULL;
  54 #endif
  55 tTSS    *gTSSs = NULL;
  56 #if !USE_MP
  57 tTSS    gTSS0 = {0};
  58 #endif
  59
  60 // === CODE ===
  61 /**
  62  * \fn void ArchThreads_Init()
  63  * \brief Starts the process scheduler
  64  */
  65 void ArchThreads_Init()
  66 {
  67         Uint    pos = 0;
  68         #if USE_MP
  69         // -- Initialise Multiprocessing
  70         // Find MP Floating Table
  71         // - EBDA
  72         for(pos = KERNEL_BASE|0x9FC00; pos < (KERNEL_BASE|0xA0000); pos += 16) {
  73                 if( *(Uint*)(pos) == MPTABLE_IDENT ) {
  74                         if(ByteSum( (void*)pos, sizeof(tMPInfo) ) != 0) continue;
  75                         gMPTable = (void*)pos;
  76                         break;
  77                 }
  78         }
  79         // - Last KiB
  80         if(!gMPTable) {
  81
  82         }
  83         // - BIOS ROM
  84         if(!gMPTable) {
  85                 for(pos = KERNEL_BASE|0xF0000; pos < (KERNEL_BASE|0x100000); pos += 16) {
  86                         if( *(Uint*)(pos) == MPTABLE_IDENT ) {
  87                                 if(ByteSum( (void*)pos, sizeof(tMPInfo) ) != 0) continue;
  88                                 gMPTable = (void*)pos;
  89                                 break;
  90                         }
  91                 }
  92         }
  93
  94         // If the MP Table Exists, parse it
  95         if(gMPTable)
  96         {
  97                 Panic("Uh oh... MP Table Parsing is unimplemented\n");
  98         } else {
  99         #endif
 100                 giNumCPUs = 1;
 101                 gTSSs = &gTSS0;
 102         #if USE_MP
 103         }
 104
 105         // Initialise TSS
 106         for(pos=0;pos<giNumCPUs;pos++)
 107         {
 108         #else
 109         pos = 0;
 110         #endif
 111                 gTSSs[pos].SS0 = 0x10;
 112                 gTSSs[pos].ESP0 = 0;    // Set properly by scheduler
 113                 gGDT[5+pos].LimitLow = sizeof(tTSS);
 114                 gGDT[5+pos].LimitHi = 0;
 115                 gGDT[5+pos].Access = 0x89;      // Type
 116                 gGDT[5+pos].Flags = 0x4;
 117                 gGDT[5+pos].BaseLow = (Uint)&gTSSs[pos] & 0xFFFF;
 118                 gGDT[5+pos].BaseMid = (Uint)&gTSSs[pos] >> 16;
 119                 gGDT[5+pos].BaseHi = (Uint)&gTSSs[pos] >> 24;
 120         #if USE_MP
 121         }
 122         for(pos=0;pos<giNumCPUs;pos++) {
 123         #endif
 124                 __asm__ __volatile__ ("ltr %%ax"::"a"(0x28+pos*8));
 125         #if USE_MP
 126         }
 127         #endif
 128
 129         #if USE_MP
 130         gCurrentThread[0] = &gThreadZero;
 131         #else
 132         gCurrentThread = &gThreadZero;
 133         #endif
 134
 135         #if USE_PAE
 136         gThreadZero.MemState.PDP[0] = 0;
 137         gThreadZero.MemState.PDP[1] = 0;
 138         gThreadZero.MemState.PDP[2] = 0;
 139         #else
 140         gThreadZero.MemState.CR3 = (Uint)gaInitPageDir - KERNEL_BASE;
 141         #endif
 142
 143         // Set timer frequency
 144         outb(0x43, 0x34);       // Set Channel 0, Low/High, Rate Generator
 145         outb(0x40, TIMER_DIVISOR&0xFF); // Low Byte of Divisor
 146         outb(0x40, (TIMER_DIVISOR>>8)&0xFF);    // High Byte
 147
 148         // Create Per-Process Data Block
 149         MM_Allocate(MM_PPD_CFG);
 150
 151         // Change Stacks
 152         Proc_ChangeStack();
 153 }
 154
 155 /**
 156  * \fn void Proc_Start()
 157  * \brief Start process scheduler
 158  */
 159 void Proc_Start()
 160 {
 161         // Start Interrupts (and hence scheduler)
 162         __asm__ __volatile__("sti");
 163 }
 164
 165 /**
 166  * \fn tThread *Proc_GetCurThread()
 167  * \brief Gets the current thread
 168  */
 169 tThread *Proc_GetCurThread()
 170 {
 171         #if USE_MP
 172         return NULL;
 173         #else
 174         return gCurrentThread;
 175         #endif
 176 }
 177
 178 /**
 179  * \fn void Proc_ChangeStack()
 180  * \brief Swaps the current stack for a new one (in the proper stack reigon)
 181  */
 182 void Proc_ChangeStack()
 183 {
 184         Uint    esp, ebp;
 185         Uint    tmpEbp, oldEsp;
 186         Uint    curBase, newBase;
 187
 188         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 189         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 190
 191         oldEsp = esp;
 192
 193         // Create new KStack
 194         newBase = MM_NewKStack();
 195         // Check for errors
 196         if(newBase == 0) {
 197                 Panic("What the?? Unable to allocate space for initial kernel stack");
 198                 return;
 199         }
 200
 201         curBase = (Uint)&Kernel_Stack_Top;
 202
 203         LOG("curBase = 0x%x, newBase = 0x%x", curBase, newBase);
 204
 205         // Get ESP as a used size
 206         esp = curBase - esp;
 207         LOG("memcpy( %p, %p, 0x%x )", (void*)(newBase - esp), (void*)(curBase - esp), esp );
 208         // Copy used stack
 209         memcpy( (void*)(newBase - esp), (void*)(curBase - esp), esp );
 210         // Get ESP as an offset in the new stack
 211         esp = newBase - esp;
 212         // Adjust EBP
 213         ebp = newBase - (curBase - ebp);
 214
 215         // Repair EBPs & Stack Addresses
 216         // Catches arguments also, but may trash stack-address-like values
 217         for(tmpEbp = esp; tmpEbp < newBase; tmpEbp += 4)
 218         {
 219                 if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < curBase)
 220                         *(Uint*)tmpEbp += newBase - curBase;
 221         }
 222
 223         gCurrentThread->KernelStack = newBase;
 224
 225         __asm__ __volatile__ ("mov %0, %%esp"::"r"(esp));
 226         __asm__ __volatile__ ("mov %0, %%ebp"::"r"(ebp));
 227 }
 228
 229 /**
 230  * \fn int Proc_Clone(Uint *Err, Uint Flags)
 231  * \brief Clone the current process
 232  */
 233 int Proc_Clone(Uint *Err, Uint Flags)
 234 {
 235         tThread *newThread;
 236         Uint    eip, esp, ebp;
 237
 238         __asm__ __volatile__ ("mov %%esp, %0": "=r"(esp));
 239         __asm__ __volatile__ ("mov %%ebp, %0": "=r"(ebp));
 240
 241         // Create new thread structure
 242         newThread = malloc( sizeof(tThread) );
 243         if(!newThread) {
 244                 Warning("Proc_Clone - Out of memory when creating thread\n");
 245                 *Err = -ENOMEM;
 246                 return -1;
 247         }
 248         // Base new thread on old
 249         memcpy(newThread, gCurrentThread, sizeof(tThread));
 250         // Initialise Memory Space (New Addr space or kernel stack)
 251         if(Flags & CLONE_VM) {
 252                 newThread->TGID = newThread->TID;
 253                 newThread->MemState.CR3 = MM_Clone();
 254         } else {
 255                 Uint    tmpEbp, oldEsp = esp;
 256
 257                 // Create new KStack
 258                 newThread->KernelStack = MM_NewKStack();
 259                 // Check for errors
 260                 if(newThread->KernelStack == 0) {
 261                         free(newThread);
 262                         return -1;
 263                 }
 264
 265                 // Get ESP as a used size
 266                 esp = gCurrentThread->KernelStack - esp;
 267                 // Copy used stack
 268                 memcpy( (void*)(newThread->KernelStack - esp), (void*)(gCurrentThread->KernelStack - esp), esp );
 269                 // Get ESP as an offset in the new stack
 270                 esp = newThread->KernelStack - esp;
 271                 // Adjust EBP
 272                 ebp = newThread->KernelStack - (gCurrentThread->KernelStack - ebp);
 273
 274                 // Repair EBPs & Stack Addresses
 275                 // Catches arguments also, but may trash stack-address-like values
 276                 for(tmpEbp = esp; tmpEbp < newThread->KernelStack; tmpEbp += 4)
 277                 {
 278                         if(oldEsp < *(Uint*)tmpEbp && *(Uint*)tmpEbp < gCurrentThread->KernelStack)
 279                                 *(Uint*)tmpEbp += newThread->KernelStack - gCurrentThread->KernelStack;
 280                 }
 281         }
 282
 283         // Set Pointer, Spinlock and TID
 284         newThread->Next = NULL;
 285         newThread->IsLocked = 0;
 286         newThread->TID = giNextTID++;
 287         newThread->PTID = gCurrentThread->TID;
 288
 289         // Clear message list (messages are not inherited)
 290         newThread->Messages = NULL;
 291         newThread->LastMessage = NULL;
 292
 293         // Set remaining (sheduler expects remaining to be correct)
 294         newThread->Remaining = newThread->Quantum;
 295
 296         // Save core machine state
 297         newThread->SavedState.ESP = esp;
 298         newThread->SavedState.EBP = ebp;
 299         eip = GetEIP();
 300         if(eip == SWITCH_MAGIC) {
 301                 outb(0x20, 0x20);       // ACK Timer and return as child
 302                 return 0;
 303         }
 304
 305         // Set EIP as parent
 306         newThread->SavedState.EIP = eip;
 307
 308         // Lock list and add to active
 309         LOCK( &giThreadListLock );
 310         newThread->Next = gActiveThreads;
 311         gActiveThreads = newThread;
 312         giNumActiveThreads ++;
 313         giTotalTickets += newThread->NumTickets;
 314         RELEASE( &giThreadListLock );
 315
 316         Threads_Dump();
 317
 318         return newThread->TID;
 319 }
 320
 321 /**
 322  * \fn Uint Proc_MakeUserStack()
 323  * \brief Creates a new user stack
 324  */
 325 Uint Proc_MakeUserStack()
 326 {
 327          int    i;
 328         Uint    base = USER_STACK_TOP - USER_STACK_SZ;
 329
 330         // Check Prospective Space
 331         for( i = USER_STACK_SZ >> 12; i--; )
 332                 if( MM_GetPhysAddr( base + (i<<12) ) != 0 )
 333                         break;
 334
 335         if(i != -1)     return 0;
 336
 337         // Allocate Stack - Allocate incrementally to clean up MM_Dump output
 338         for( i = 0; i < USER_STACK_SZ/4069; i++ )
 339                 MM_Allocate( base + (i<<12) );
 340
 341         return base + USER_STACK_SZ;
 342 }
 343
 344
 345 /**
 346  * \fn void Proc_StartUser(Uint Entrypoint, Uint Base, int ArgC, char **ArgV, char **EnvP, int DataSize)
 347  * \brief Starts a user task
 348  */
 349 void Proc_StartUser(Uint Entrypoint, Uint *Bases, int ArgC, char **ArgV, char **EnvP, int DataSize)
 350 {
 351         Uint    *stack = (void*)Proc_MakeUserStack();
 352          int    i;
 353         Uint    delta;
 354         Uint16  ss, cs;
 355
 356         LOG("stack = 0x%x", stack);
 357
 358         // Copy Arguments
 359         stack = (void*)( (Uint)stack - DataSize );
 360         memcpy( stack, ArgV, DataSize );
 361
 362         // Adjust Arguments and environment
 363         delta = (Uint)stack - (Uint)ArgV;
 364         ArgV = (char**)stack;
 365         for( i = 0; ArgV[i]; i++ )      ArgV[i] += delta;
 366         i ++;
 367         EnvP = &ArgV[i];
 368         for( i = 0; EnvP[i]; i++ )      EnvP[i] += delta;
 369
 370         // User Mode Segments
 371         ss = 0x23;      cs = 0x1B;
 372
 373         // Arguments
 374         *--stack = (Uint)EnvP;
 375         *--stack = (Uint)ArgV;
 376         *--stack = (Uint)ArgC;
 377         while(*Bases)
 378                 *--stack = *Bases++;
 379         *--stack = 0;   // Return Address
 380         delta = (Uint)stack;    // Reuse delta to save SP
 381
 382         *--stack = ss;          //Stack Segment
 383         *--stack = delta;       //Stack Pointer
 384         *--stack = 0x0202;      //EFLAGS (Resvd (0x2) and IF (0x20))
 385         *--stack = cs;          //Code Segment
 386         *--stack = Entrypoint;  //EIP
 387         //PUSHAD
 388         *--stack = 0xAAAAAAAA;  // eax
 389         *--stack = 0xCCCCCCCC;  // ecx
 390         *--stack = 0xDDDDDDDD;  // edx
 391         *--stack = 0xBBBBBBBB;  // ebx
 392         *--stack = 0xD1D1D1D1;  // edi
 393         *--stack = 0x54545454;  // esp - NOT POPED
 394         *--stack = 0x51515151;  // esi
 395         *--stack = 0xB4B4B4B4;  // ebp
 396         //Individual PUSHs
 397         *--stack = ss;  // ds
 398         *--stack = ss;  // es
 399         *--stack = ss;  // fs
 400         *--stack = ss;  // gs
 401
 402         __asm__ __volatile__ (
 403         "mov %%eax,%%esp;\n\t"  // Set stack pointer
 404         "pop %%gs;\n\t"
 405         "pop %%fs;\n\t"
 406         "pop %%es;\n\t"
 407         "pop %%ds;\n\t"
 408         "popa;\n\t"
 409         "iret;\n\t" : : "a" (stack));
 410         for(;;);
 411 }
 412
 413 /**
 414  * \fn int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 415  * \brief Demotes a process to a lower permission level
 416  * \param Err   Pointer to user's errno
 417  */
 418 int Proc_Demote(Uint *Err, int Dest, tRegs *Regs)
 419 {
 420          int    cpl = Regs->cs & 3;
 421         // Sanity Check
 422         if(Dest > 3 || Dest < 0) {
 423                 *Err = -EINVAL;
 424                 return -1;
 425         }
 426
 427         // Permission Check
 428         if(cpl > Dest) {
 429                 *Err = -EACCES;
 430                 return -1;
 431         }
 432
 433         // Change the Segment Registers
 434         Regs->cs = (((Dest+1)<<4) | Dest) - 8;
 435         Regs->ss = ((Dest+1)<<4) | Dest;
 436         // Check if the GP Segs are GDT, then change them
 437         if(!(Regs->ds & 4))     Regs->ds = ((Dest+1)<<4) | Dest;
 438         if(!(Regs->es & 4))     Regs->es = ((Dest+1)<<4) | Dest;
 439         if(!(Regs->fs & 4))     Regs->fs = ((Dest+1)<<4) | Dest;
 440         if(!(Regs->gs & 4))     Regs->gs = ((Dest+1)<<4) | Dest;
 441
 442         return 0;
 443 }
 444
 445 /**
 446  * \fn void Proc_Scheduler(int CPU)
 447  * \brief Swap current thread and clears dead threads
 448  */
 449 void Proc_Scheduler(int CPU)
 450 {
 451         Uint    esp, ebp, eip;
 452         tThread *thread;
 453
 454         // If the spinlock is set, let it complete
 455         if(giThreadListLock)    return;
 456
 457         // Clear Delete Queue
 458         while(gDeleteThreads)
 459         {
 460                 thread = gDeleteThreads->Next;
 461                 if(gDeleteThreads->IsLocked) {  // Only free if structure is unused
 462                         gDeleteThreads->Status = THREAD_STAT_NULL;
 463                         free( gDeleteThreads );
 464                 }
 465                 gDeleteThreads = thread;
 466         }
 467
 468         // Check if there is any tasks running
 469         if(giNumActiveThreads == 0) {
 470                 Log("No Active threads, sleeping");
 471                 __asm__ __volatile__ ("hlt");
 472                 return;
 473         }
 474
 475         // Reduce remaining quantum and continue timeslice if non-zero
 476         if(gCurrentThread->Remaining--) return;
 477         // Reset quantum for next call
 478         gCurrentThread->Remaining = gCurrentThread->Quantum;
 479
 480         // Get machine state
 481         __asm__ __volatile__ ("mov %%esp, %0":"=r"(esp));
 482         __asm__ __volatile__ ("mov %%ebp, %0":"=r"(ebp));
 483         eip = GetEIP();
 484         if(eip == SWITCH_MAGIC) return; // Check if a switch happened
 485
 486         // Save machine state
 487         gCurrentThread->SavedState.ESP = esp;
 488         gCurrentThread->SavedState.EBP = ebp;
 489         gCurrentThread->SavedState.EIP = eip;
 490
 491         // Get next thread
 492         thread = Threads_GetNextToRun(CPU);
 493
 494         // Error Check
 495         if(thread == NULL) {
 496                 Warning("Hmm... Threads_GetNextToRun returned NULL, I don't think this should happen.\n");
 497                 return;
 498         }
 499
 500         // Set current thread
 501         gCurrentThread = thread;
 502
 503         // Update Kernel Stack pointer
 504         gTSSs[CPU].ESP0 = thread->KernelStack;
 505
 506         // Set address space
 507         __asm__ __volatile__ ("mov %0, %%cr3"::"a"(gCurrentThread->MemState.CR3));
 508         // Switch threads
 509         __asm__ __volatile__ (
 510                 "mov %1, %%esp\n\t"
 511                 "mov %2, %%ebp\n\t"
 512                 "jmp *%3" : :
 513                 "a"(SWITCH_MAGIC), "b"(gCurrentThread->SavedState.ESP),
 514                 "d"(gCurrentThread->SavedState.EBP), "c"(gCurrentThread->SavedState.EIP));
 515         for(;;);        // Shouldn't reach here
 516 }