init: init nachos hw01, should pass jenkins os_group_20_hw job but fail on os_group_20_ta job
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TA
132
code/userprog/exception.cc
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132
code/userprog/exception.cc
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// exception.cc
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// Entry point into the Nachos kernel from user programs.
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// There are two kinds of things that can cause control to
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// transfer back to here from user code:
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//
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// syscall -- The user code explicitly requests to call a procedure
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// in the Nachos kernel. Right now, the only function we support is
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// "Halt".
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//
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// exceptions -- The user code does something that the CPU can't handle.
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// For instance, accessing memory that doesn't exist, arithmetic errors,
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// etc.
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//
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// Interrupts (which can also cause control to transfer from user
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// code into the Nachos kernel) are handled elsewhere.
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//
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// For now, this only handles the Halt() system call.
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// Everything else core dumps.
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//
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// Copyright (c) 1992-1996 The Regents of the University of California.
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// All rights reserved. See copyright.h for copyright notice and limitation
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// of liability and disclaimer of warranty provisions.
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#include "copyright.h"
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#include "main.h"
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#include "syscall.h"
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#include "ksyscall.h"
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//----------------------------------------------------------------------
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// ExceptionHandler
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// Entry point into the Nachos kernel. Called when a user program
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// is executing, and either does a syscall, or generates an addressing
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// or arithmetic exception.
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//
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// For system calls, the following is the calling convention:
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//
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// system call code -- r2
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// arg1 -- r4
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// arg2 -- r5
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// arg3 -- r6
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// arg4 -- r7
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//
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// The result of the system call, if any, must be put back into r2.
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//
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// If you are handling a system call, don't forget to increment the pc
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// before returning. (Or else you'll loop making the same system call forever!)
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//
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// "which" is the kind of exception. The list of possible exceptions
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// is in machine.h.
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//----------------------------------------------------------------------
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void
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ExceptionHandler(ExceptionType which)
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{
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int type = kernel->machine->ReadRegister(2);
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int val;
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int status, exit, threadID, programID;
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DEBUG(dbgSys, "Received Exception " << which << " type: " << type << "\n");
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switch (which) {
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case SyscallException:
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switch(type) {
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case SC_Halt:
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DEBUG(dbgSys, "Shutdown, initiated by user program.\n");
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SysHalt();
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cout<<"in exception\n";
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ASSERTNOTREACHED();
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break;
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case SC_MSG:
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DEBUG(dbgSys, "Message received.\n");
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val = kernel->machine->ReadRegister(4);
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{
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char *msg = &(kernel->machine->mainMemory[val]);
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cout << msg << endl;
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}
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SysHalt();
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ASSERTNOTREACHED();
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break;
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case SC_Create:
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val = kernel->machine->ReadRegister(4);
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{
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char *filename = &(kernel->machine->mainMemory[val]);
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//cout << filename << endl;
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status = SysCreate(filename);
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kernel->machine->WriteRegister(2, (int) status);
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}
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kernel->machine->WriteRegister(PrevPCReg, kernel->machine->ReadRegister(PCReg));
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kernel->machine->WriteRegister(PCReg, kernel->machine->ReadRegister(PCReg) + 4);
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kernel->machine->WriteRegister(NextPCReg, kernel->machine->ReadRegister(PCReg)+4);
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return;
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ASSERTNOTREACHED();
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break;
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case SC_Add:
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DEBUG(dbgSys, "Add " << kernel->machine->ReadRegister(4) << " + " << kernel->machine->ReadRegister(5) << "\n");
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/* Process SysAdd Systemcall*/
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int result;
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result = SysAdd(/* int op1 */(int)kernel->machine->ReadRegister(4),
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/* int op2 */(int)kernel->machine->ReadRegister(5));
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DEBUG(dbgSys, "Add returning with " << result << "\n");
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/* Prepare Result */
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kernel->machine->WriteRegister(2, (int)result);
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/* Modify return point */
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{
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/* set previous programm counter (debugging only)*/
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kernel->machine->WriteRegister(PrevPCReg, kernel->machine->ReadRegister(PCReg));
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/* set programm counter to next instruction (all Instructions are 4 byte wide)*/
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kernel->machine->WriteRegister(PCReg, kernel->machine->ReadRegister(PCReg) + 4);
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/* set next programm counter for brach execution */
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kernel->machine->WriteRegister(NextPCReg, kernel->machine->ReadRegister(PCReg)+4);
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}
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cout << "result is " << result << "\n";
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return;
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ASSERTNOTREACHED();
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break;
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case SC_Exit:
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DEBUG(dbgAddr, "Program exit\n");
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val=kernel->machine->ReadRegister(4);
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cout << "return value:" << val << endl;
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kernel->currentThread->Finish();
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break;
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default:
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cerr << "Unexpected system call " << type << "\n";
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break;
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}
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break;
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default:
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cerr << "Unexpected user mode exception " << (int)which << "\n";
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break;
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}
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ASSERTNOTREACHED();
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}
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