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Revamped dump extensions to accept argument arrays, added probeDesc() for Debugger-safe segment descriptor loading

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This commit is contained in:
Jeff Parsons 2015-09-03 09:07:40 -07:00
commit ee2f5ff761
9 changed files with 340 additions and 219 deletions
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76
modules/pcjs/lib/x86seg.js
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@ -225,11 +225,11 @@ X86Seg.prototype.loadProt = function loadProt(sel, fProbe)
/*
* The ROM BIOS POST executes some test code in protected-mode without properly initializing the LDT,
* which has no bearing on the ROM's own code, because it never loads any LDT selectors, but if at the same
* time our Debugger attempts to validate a selector in one of its breakpoints, that could cause some
* grief here. We avoid that grief by skipping segment lookup if the descriptor table being referenced is zero
* AND the Debugger's ID.DBG segment register is being used.
* time our Debugger attempts to validate a selector in one of its breakpoints, that could cause some grief.
*
* Fortunately, the Debugger now has its own interface, probeDesc(), so that should no longer be a concern.
*/
if (addrDT || this.id != X86Seg.ID.DBG) {
if (addrDT) {
var addrDesc = (addrDT + (sel & X86.SEL.MASK))|0;
if ((addrDTLimit - addrDesc)|0 >= 7) {
/*
@ -238,7 +238,7 @@ X86Seg.prototype.loadProt = function loadProt(sel, fProbe)
* starting with a 15-cycle difference. Obviously the difference will vary with the instruction,
* and will be much greater whenever the load fails.
*/
if (this.id != X86Seg.ID.DBG) cpu.nStepCycles -= 15;
cpu.nStepCycles -= 15;
return this.loadDesc8(addrDesc, sel, fProbe);
}
if (this.id < X86Seg.ID.VER) {
@ -740,7 +740,6 @@ X86Seg.prototype.loadDesc8 = function(addrDesc, sel, fProbe)
if (!I386 || !(type & X86.DESC.ACC.NONSEG_386)) {
offSP = (cplNew << 2) + X86.TSS286.CPL0_SP;
lenSP = 2;
cpu.assert(!(regPS & X86.PS.VM));
} else {
offSP = (cplNew << 2) + X86.TSS386.CPL0_ESP;
lenSP = 4;
@ -923,8 +922,9 @@ X86Seg.prototype.loadDesc8 = function(addrDesc, sel, fProbe)
default:
/*
* The only other case should be X86Seg.ID.DBG, for which we do nothing.
* The only other case used to be X86Seg.ID.DBG, but the Debugger uses probeDesc() now, so we should never get here.
*/
cpu.assert(false);
break;
}
@ -946,7 +946,7 @@ X86Seg.prototype.loadDesc8 = function(addrDesc, sel, fProbe)
this.ext = ext;
this.addrDesc = addrDesc;
/*
* A quick recap of what updateMode(fLoad=true, fProt=true, fV86=false) actually updates next:
* A quick recap of what updateMode(fLoad=true, fProt=true, fV86=false) actually updates:
*
* cpl
* dpl
@ -968,6 +968,64 @@ X86Seg.prototype.loadDesc8 = function(addrDesc, sel, fProbe)
return base;
};
/**
* probeDesc(sel)
*
* This is a neutered version of loadProt() designed for the Debugger.
*
* @this {X86Seg}
* @param {number} sel
* @return {number} base address of selected segment, or X86.ADDR_INVALID if error
*/
X86Seg.prototype.probeDesc = function(sel)
{
var addrDT;
var addrDTLimit;
var cpu = this.cpu;
sel &= 0xffff;
if (!(sel & X86.SEL.LDT)) {
addrDT = cpu.addrGDT;
addrDTLimit = cpu.addrGDTLimit;
} else {
addrDT = cpu.segLDT.base;
addrDTLimit = (addrDT + cpu.segLDT.limit)|0;
}
var addrDesc = (addrDT + (sel & X86.SEL.MASK))|0;
if ((addrDTLimit - addrDesc)|0 >= 7) {
/*
* Load the descriptor from memory using probeAddr().
*/
var limit = cpu.probeAddr(addrDesc + X86.DESC.LIMIT.OFFSET, 2);
var acc = cpu.probeAddr(addrDesc + X86.DESC.ACC.OFFSET, 2);
var type = (acc & X86.DESC.ACC.TYPE.MASK);
var base = cpu.probeAddr(addrDesc + X86.DESC.BASE.OFFSET, 2) | ((acc & X86.DESC.ACC.BASE1623) << 16);
var ext = cpu.probeAddr(addrDesc + X86.DESC.EXT.OFFSET, 2);
if (I386 && cpu.model >= X86.MODEL_80386) {
base |= (ext & X86.DESC.EXT.BASE2431) << 16;
limit |= (ext & X86.DESC.EXT.LIMIT1619) << 16;
if (ext & X86.DESC.EXT.LIMITPAGES) limit = (limit << 12) | 0xfff;
}
this.sel = sel;
this.base = base;
this.limit = limit;
this.offMax = (limit >>> 0) + 1;
this.acc = acc;
this.type = type;
this.ext = ext;
this.addrDesc = addrDesc;
this.updateMode(true, true, false);
return base;
}
return X86.ADDR_INVALID;
};
/**
* switchTSS(selNew, fNest)
*
@ -1408,7 +1466,7 @@ X86Seg.prototype.updateMode = function(fLoad, fProt, fV86)
X86Seg.prototype.messageSeg = function(sel, base, limit, type, ext)
{
if (DEBUG) {
if (DEBUGGER && this.id != X86Seg.ID.DBG && this.dbg && this.dbg.messageEnabled(Messages.SEG)) {
if (DEBUGGER && this.dbg && this.dbg.messageEnabled(Messages.SEG)) {
var ch = (this.sName.length < 3? " " : "");
var sDPL = " dpl=" + this.dpl;
if (this.id == X86Seg.ID.CODE) sDPL += " cpl=" + this.cpl;