Retro/pcjs
Watch
1
0
Fork
You've already forked pcjs
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

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

Browse source
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
Download patch file Download diff file Expand all files Collapse all files

18
modules/pcjs/lib/x86op0f.js
View file

@ -1332,6 +1332,24 @@ X86.aOps0F[0x06] = X86.opCLTS;
*/
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) {
X86.aOps0F386 = [];
X86.aOps0F386[0x20] = X86.opMOVrc;