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Add 0x0F,0xFF to the ranks of invalid opcodes (as opposed to undefined)

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This commit is contained in:
Jeff Parsons 2015-07-16 14:10:23 -07:00
commit a6c418ff3f
3 changed files with 19 additions and 2 deletions
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2
modules/pcjs/lib/x86.js
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@ -230,7 +230,7 @@ var X86 = {
* Interrupts beyond 0x10 (up through 0x1F) are reserved for future exceptions. * Interrupts beyond 0x10 (up through 0x1F) are reserved for future exceptions.
* *
* Implementation Detail: For any opcode we know must generate a UD_FAULT interrupt, we invoke opInvalid(), * Implementation Detail: For any opcode we know must generate a UD_FAULT interrupt, we invoke opInvalid(),
* NOT opUndefined(). UD_FAULT is for INVALID opcodes, Intel's choice of "UD" notwithstanding. * NOT opUndefined(). UD_FAULT is for INVALID opcodes, Intel's choice of term "undefined" notwithstanding.
* *
* We reserve the term "undefined" for opcodes that require more investigation, and we invoke opUndefined() * We reserve the term "undefined" for opcodes that require more investigation, and we invoke opUndefined()
* ONLY until an opcode's behavior has finally been defined, at which point it becomes either valid or invalid. * ONLY until an opcode's behavior has finally been defined, at which point it becomes either valid or invalid.

18
modules/pcjs/lib/x86op0f.js
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@ -1332,6 +1332,24 @@ X86.aOps0F[0x06] = X86.opCLTS;
*/ */
X86.aOps0F[0x0B] = X86.opInvalid; X86.aOps0F[0x0B] = X86.opInvalid;
/*
* NOTE: Any other opcode slots NOT explicitly initialized above with either a dedicated function OR opInvalid()
* will be set to opUndefined() when initProcessor() finalizes the opcode tables. If the processor is an 80386,
* initProcessor() will also incorporate all the handlers listed below in aOps0F386.
*
* A call to opUndefined() implies something serious has occurred that merits our attention (eg, perhaps someone
* is using an undocumented opcode that we haven't implemented yet), whereas a call to opInvalid() may or may not.
*
* For example, when Windows initializes in protected-mode, it sets a DPMI exception handler for UD_FAULT and
* then attempts to generate that exception with undefined opcode 0x0F,0xFF. Apparently, whoever wrote that code
* (davidw?) didn't get the Intel memo regarding the preferred invalid opcode (0x0F,0x0B, aka UD2), or perhaps Intel
* hadn't written that memo yet -- although if that's the case, then Intel should have followed Microsoft's lead and
* selected 0x0F,0xFF instead of 0x0F,0x0B.
*
* In any case, this means we need to explicitly set the handler for that opcode to opInvalid(), too.
*/
X86.aOps0F[0xFF] = X86.opInvalid;
if (I386) { if (I386) {
X86.aOps0F386 = []; X86.aOps0F386 = [];
X86.aOps0F386[0x20] = X86.opMOVrc; X86.aOps0F386[0x20] = X86.opMOVrc;

1
modules/pcjs/lib/x86ops.js
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@ -4017,7 +4017,6 @@ X86.opGRP4w = function GRP4w()
X86.opInvalid = function opInvalid() X86.opInvalid = function opInvalid()
{ {
X86.fnFault.call(this, X86.EXCEPTION.UD_FAULT); X86.fnFault.call(this, X86.EXCEPTION.UD_FAULT);
this.stopCPU();
}; };
/** /**