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Fixed divide-by-zero and data breakpoint exception dispatching

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This commit is contained in:
Jeff Parsons 2015-10-18 10:57:51 -07:00
commit d1d733e38b
8 changed files with 144 additions and 105 deletions
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37
modules/pcjs/lib/x86ops.js
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@ -3613,33 +3613,12 @@ X86.opINT3 = function INT3()
return;
}
/*
* To give our own Debugger the ability to stop execution on INT3, I thought about treating this as
* a fault rather than an interrupt, in order to leverage the existing Debugger logic inside fnFault()
* processing, but that has the unwanted side-effect of rewinding EIP to the INT3 prior to issuing
* the interrupt, and the corresponding IRET takes us right back to the INT3.
*
* X86.fnFault.call(this, X86.EXCEPTION.BREAKPOINT, null, false, this.cycleCounts.nOpCyclesInt3D);
*
* Then I had the idea of using the fnFaultMessage() function, in much the same way that fnFault()
* does for actual faults: if the user turned on the FAULT and HALT message bits, then fnFaultMessage()
* would tell us to halt; otherwise, we'd perform the normal fnINT() call.
*
* if (X86.fnFaultMessage.call(this, X86.EXCEPTION.BREAKPOINT)) {
* this.setIP(this.opLIP - this.segCS.base);
* return;
* }
*
* However, that makes it a little tedious to get past the INT3 (you have to use a Debugger command
* like "t;g"), and a somewhat confusing fault message is displayed; eg:
*
* Fault 0x03 on opcode 0xB4 at 09CE:0155 (%009E35)
*
* The best solution was to leave this function alone, and change the Debugger's checkBreakpoint()
* function to stop execution on INT3 whenever both the INT and HALT message bits are set; a simple "g"
* command allows you to continue.
* Because INT3 is a trap, not a fault, we must use fnTrap() rather than fnFault(). Unfortunately, that
* means you can't rely on the Debugger logic instead fnFault() to conditionally stop execution on an INT3,
* so I've changed the Debugger's checkBreakpoint() function to stop execution on INT3 whenever both the
* INT and HALT message bits are set; a simple "g" command allows you to continue.
*/
this.nFault = -1;
X86.fnINT.call(this, X86.EXCEPTION.BREAKPOINT, null, this.cycleCounts.nOpCyclesInt3D);
X86.fnTrap.call(this, X86.EXCEPTION.BP_TRAP, this.cycleCounts.nOpCyclesInt3D);
};
/**
@ -3663,8 +3642,7 @@ X86.opINTn = function INTn()
* and returns false ONLY if a notification handler returned false (ie, requesting the interrupt be skipped).
*/
if (this.checkIntNotify(nInt)) {
this.nFault = -1;
X86.fnINT.call(this, nInt, null, 0);
X86.fnTrap.call(this, nInt, 0);
return;
}
this.nStepCycles--; // we don't need to assess the full cost of nOpCyclesInt, but we need to assess something...
@ -3686,8 +3664,7 @@ X86.opINTO = function INTO()
X86.fnFault.call(this, X86.EXCEPTION.GP_FAULT, 0);
return;
}
this.nFault = -1;
X86.fnINT.call(this, X86.EXCEPTION.OVERFLOW, null, this.cycleCounts.nOpCyclesIntOD);
X86.fnTrap.call(this, X86.EXCEPTION.OF_TRAP, this.cycleCounts.nOpCyclesIntOD);
return;
}
this.nStepCycles -= this.cycleCounts.nOpCyclesIntOFall;