--- /dev/null
+; MMURTL Operating System Source Code\r
+; Copyright 1991,1992,1993,1994 Richard A. Burgess\r
+; ALL RIGHTS RESERVED\r
+; Version 1.0\r
+.DATA\r
+.INCLUDE MOSEDF.INC\r
+.INCLUDE TSS.INC\r
+.INCLUDE JOB.INC\r
+\r
+EXTRN DbgpTSSSave DD\r
+EXTRN dbgFAULT DD\r
+EXTRN dbgFltErc DD\r
+EXTRN dbgOldEIP DD\r
+EXTRN dbgOldCS DD\r
+EXTRN dbgOldEFlgs DD\r
+\r
+EXTRN DbgTSS DB\r
+EXTRN pRunTSS DD\r
+\r
+.CODE\r
+\r
+;This file contains Exception Handlers and Debugger Entry\r
+;and Exit code.\r
+\r
+;=============================================================================\r
+; Procedure jumped to by interrupt procedures to enter debugger\r
+;=============================================================================\r
+;EnterDebug\r
+;\r
+; This piece of code sets up to enter the debugger. If we get here,\r
+; one of the exceptions has activated and has done a little work based\r
+; on which exception is was, then it jumped here to enter the debugger.\r
+; This code effectively replaces the interrupted task with the debugger\r
+; task (without going through the kernel). First we copy the Page Dir\r
+; entry from the current job into the debuggers job, then copy the CR3\r
+; register from the current TSS into the debugger's TSS. This makes the\r
+; debugger operate in the current tasks memory space. All of the debugger's\r
+; code and data are in OS protected pages (which are shared with all tasks),\r
+; so this is OK to do even if the offending task referenced a bogus address.\r
+; Next, we save the current pRunTSS and place the debugger's TSS in\r
+; pRunTSS, then jump to the debugger's selector. This switches tasks.\r
+;\r
+EnterDebug:\r
+ PUSH EAX ;we MUST save caller's registers\r
+ PUSH EBX ; and restore them before the\r
+ PUSH EDX ; task switch into the debugger\r
+\r
+ MOV EAX, pRunTSS ;pRunTSS -> EAX\r
+ MOV EBX, [EAX+TSS_CR3] ;current CR3 -> EBX\r
+ MOV EDX, OFFSET DbgTSS ;pDebuggerTSS -> EDX\r
+ MOV [EDX+TSS_CR3], EBX ;CR3 -> DebuggerTSS\r
+\r
+ MOV EAX, [EAX+TSS_pJCB] ;pCrntJCB -> EAX\r
+ MOV EDX, [EDX+TSS_pJCB] ;pDebuggerJCB -> EDX\r
+ MOV EBX, [EAX+JcbPD] ;CrntJob Page Dir -> EBX\r
+ MOV [EDX+JcbPD], EBX ;Page Dir -> Debugger JCB\r
+\r
+ MOV EAX, pRunTSS ;Save the current pRunTSS\r
+ MOV DbgpTSSSave, EAX\r
+ MOV EAX, OFFSET DbgTSS ;Install Debugger's as current\r
+ MOV pRunTSS, EAX ;Set Dbgr as running task\r
+\r
+ MOV BX, [EAX+Tid]\r
+ MOV TSS_Sel, BX ;Set up debugger selector\r
+\r
+ POP EDX ;make his registers right!\r
+ POP EBX\r
+ POP EAX\r
+\r
+ JMP FWORD PTR [TSS] ;Switch tasks to debugger\r
+\r
+ ;When the debugger exits, we come here\r
+\r
+ PUSH dbgOldEFlgs ;Put the stack back the way it was\r
+ PUSH dbgOldCS ;\r
+ PUSH dbgOldEIP ;\r
+ IRETD ;Go back to the caller\r
+\r
+;=============================================================================\r
+; INTERRUPT PROCEDURES FOR FAULTS\r
+;=============================================================================\r
+; This is the general purpose "We didn't expect this interrupt" interrupt\r
+; This will place "99" in the upper left corner of the screen so we\r
+; can see there are SPURIOUS interrupts!!!!!\r
+\r
+PUBLIC INTQ:\r
+ PUSH EAX\r
+ MOV EAX,07390739h ;99 - All unassigned ints come here\r
+ MOV DS:VGATextBase+00h,EAX\r
+ POP EAX\r
+ IRETD\r
+\r
+;===================== Divide By ZERO (Int 0) ============================\r
+\r
+PUBLIC IntDivBy0:\r
+; MOV EAX,07300730h ;00\r
+; MOV DS:VGATextBase+00h,EAX\r
+; CLI\r
+; HLT\r
+\r
+ MOV dbgFAULT,00h ; Divide By Zero\r
+ POP dbgOldEIP ; Get EIP of offender for debugger\r
+ POP dbgOldCS ;\r
+ POP dbgOldEFlgs ;\r
+ JMP EnterDebug ;Enter debugger\r
+\r
+;===================== Debugger Single Step (Int 1) ======================\r
+\r
+PUBLIC IntDbgSS:\r
+\r
+ POP dbgOldEIP ; Get EIP of offender for debugger\r
+ POP dbgOldCS ;\r
+ POP dbgOldEFlgs ;\r
+ JMP EnterDebug ;Enter debugger\r
+\r
+;===================== Debugger Entry (Int 3) ===========================\r
+\r
+PUBLIC IntDebug:\r
+\r
+ POP dbgOldEIP ; Get EIP of offender for debugger\r
+ POP dbgOldCS ; Get CS\r
+ POP dbgOldEFlgs ; Get Flags\r
+ JMP EnterDebug ;Enter debugger\r
+\r
+;===================== OverFlow (Int 4) ==================================\r
+\r
+PUBLIC IntOverFlow:\r
+ PUSH EAX\r
+ MOV EAX,07340730h ;04\r
+ MOV DS:VGATextBase+00h,EAX\r
+ CLI\r
+ HLT\r
+\r
+;========================== Bad Opcode (Int 6) ================================\r
+PUBLIC INTOpCode:\r
+; MOV EAX,07360730h ;06\r
+; MOV DS:VGATextBase+00h,EAX\r
+; HLT\r
+\r
+ MOV dbgFAULT,06h ; Invalid Opcode\r
+ POP dbgOldEIP ; Get EIP of offender for debugger\r
+ POP dbgOldCS ;\r
+ POP dbgOldEFlgs ;\r
+ JMP EnterDebug ;Enter debugger\r
+\r
+;========================== Dbl Exception (Int 08)============================\r
+PUBLIC IntDblExc:\r
+; MOV EAX,07380730h ;08\r
+; MOV DS:VGATextBase+00h,EAX\r
+; CLI\r
+; HLT\r
+\r
+ MOV dbgFAULT,08h ; Double Exception\r
+ POP dbgFltErc ; Error Code pushed last by processor\r
+ POP dbgOldEIP\r
+ POP dbgOldCS\r
+ POP dbgOldEFlgs\r
+ POP dbgOldEFlgs ;\r
+ JMP EnterDebug ;Enter debugger\r
+\r
+;========================= Invalid TSS 10 ====================================\r
+PUBLIC INTInvTss:\r
+ MOV EAX,07300731h ;10\r
+ MOV DS:VGATextBase+00h,EAX\r
+ CLI\r
+ HLT\r
+\r
+ MOV dbgFAULT,0Ah ; Invalid TSS\r
+ POP dbgFltErc ; Error code pushed last by processor\r
+ POP dbgOldEIP\r
+ POP dbgOldCS\r
+ POP dbgOldEFlgs\r
+ JMP EnterDebug ;Enter debugger\r
+\r
+;========================== Seg Not Present 11 ===============================\r
+\r
+PUBLIC INTNoSeg:\r
+ MOV EAX,07310731h ;11\r
+ MOV DS:VGATextBase+00h,EAX\r
+ CLI\r
+ HLT\r
+\r
+;========================== Stack Overflow 12 ================================\r
+PUBLIC INTStkOvr:\r
+; MOV EAX,07320731h ;12\r
+; MOV DS:VGATextBase+00h,EAX\r
+; CLI\r
+; HLT\r
+\r
+ MOV dbgFAULT,0Ch ; Stack overflow\r
+ POP dbgFltErc\r
+ POP dbgOldEIP\r
+ POP dbgOldCS\r
+ POP dbgOldEFlgs\r
+ JMP EnterDebug ;Enter debugger\r
+\r
+;========================== GP 13 ===========================================\r
+PUBLIC IntGP:\r
+; MOV EAX,07330731h ;13\r
+; MOV DS:VGATextBase+00h,EAX\r
+; CLI\r
+; HLT\r
+\r
+ MOV dbgFAULT,0Dh ; GP Fault\r
+ POP dbgFltErc\r
+ POP dbgOldEIP\r
+ POP dbgOldCS\r
+ POP dbgOldEFlgs\r
+ JMP EnterDebug ;Enter debugger\r
+\r
+;========================== Page Fault 14 ====================================\r
+PUBLIC INTPgFlt:\r
+; MOV EAX,07340731h ;14\r
+; MOV DS:VGATextBase+00h,EAX\r
+; CLI\r
+; HLT\r
+\r
+ MOV dbgFAULT,0Eh ; Page Fault\r
+ POP dbgFltErc\r
+ POP dbgOldEIP\r
+ POP dbgOldCS\r
+ POP dbgOldEFlgs\r
+ JMP EnterDebug ;Enter debugger\r
+\r
+;=============================================================================\r
+; ISR for interrupt on PICU1 from Slave\r
+;=============================================================================\r
+\r
+PUBLIC IntPICU2: ; IRQ Line 2 from Slave 8259 (Int22)\r
+ PUSH EAX\r
+ MOV EAX,07320750h ; From PICU#2 (P2)\r
+ MOV DS:VGATextBase+100h,EAX\r
+ PUSH 2\r
+ CALL FWORD PTR _EndOfIRQ\r
+ POP EAX\r
+ IRETD\r
+\r
+;=============== end of module ==================\r
projects / mmurtl / commitdiff