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Some cleanup involving invalid addresses

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This commit is contained in:
Jeff Parsons 2014-12-01 13:31:23 -08:00 • committed by jeffpar
commit c85398db6b
7 changed files with 124 additions and 82 deletions
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26
modules/pcjs/lib/x86help.js
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@ -277,7 +277,7 @@ var X86Help = {
* TODO: This instruction's 80286 documentation does not discuss conforming code segments; determine
* if we need a special check for them.
*/
if (this.segVER.load(src, true) != null) {
if (this.segVER.load(src, true) != X86.ADDR_INVALID) {
if (this.segVER.dpl >= this.segCS.cpl && this.segVER.dpl >= (src & X86.SEL.RPL)) {
this.setZF();
return this.segVER.acc & X86.DESC.ACC.MASK;
@ -304,7 +304,7 @@ var X86Help = {
* TODO: LSL is explicitly documented as ALSO requiring a non-null selector, so we check X86.SEL.MASK;
* are there any other instructions that were, um, less explicit but also require a non-null selector?
*/
if ((src & X86.SEL.MASK) && this.segVER.load(src, true) != null) {
if ((src & X86.SEL.MASK) && this.segVER.load(src, true) != X86.ADDR_INVALID) {
var fConforming = ((this.segVER.acc & X86.DESC.ACC.TYPE.CODE_CONFORMING) == X86.DESC.ACC.TYPE.CODE_CONFORMING);
if ((fConforming || this.segVER.dpl >= this.segCS.cpl) && this.segVER.dpl >= (src & X86.SEL.RPL)) {
this.setZF();
@ -456,6 +456,12 @@ var X86Help = {
/**
* opHelpINT(nIDT, nError, nCycles)
*
* NOTE: We no longer use setCSIP(), because it always loads the new CS using the segCS.load() method,
* which only knows how to load GDT and LDT selectors, whereas interrupt instructions must use setCS.loadIDT().
*
* This means we must take care to replicate critical features of setCSIP(); eg, setting segCS.fCall before
* calling loadIDT(), updating EIP, and flushing the prefetch queue.
*
* @this {X86CPU}
* @param {number} nIDT
* @param {number|null|undefined} nError
@ -471,8 +477,9 @@ var X86Help = {
var regCS = this.segCS.sel;
var regIP = this.regIP;
var base = this.segCS.loadIDT(nIDT);
if (base != null) {
if (base != X86.ADDR_INVALID) {
this.regEIP = base + this.regIP;
if (PREFETCH) this.flushPrefetch(this.regEIP);
this.pushWord(regPS);
this.pushWord(regCS);
this.pushWord(regIP);
@ -572,13 +579,14 @@ var X86Help = {
/*
* Since this fault is likely being issued in the context of an instruction that hasn't finished
* executing, and since we currently don't do anything to interrupt that execution (eg, throw a
* JavaScript exception), and since we don't want that instruction to perform any writes that might
* be destructive, we should shut off all further reads/writes for the current instruction.
* JavaScript exception), we should shut off all further reads/writes for the current instruction.
*
* As long as we're not using EAFUNCS, that's easy for any EA-based memory accesses: simply set both
* the NOREAD and NOWRITE flags. However, there may still be direct, non-EA-based memory accesses that
* could cause us grief. TODO: Implement a better solution, which may involve throwing a special
* JavaScript exception that cpu.js must intercept and quietly ignore.
* That's easy for any EA-based memory accesses (provided we're not using EAFUNCS): simply set both
* the NOREAD and NOWRITE flags. However, there are also direct, non-EA-based memory accesses to
* consider. A perfect example is opPUSHA(): if a GP fault occurs on any PUSH other than the last,
* a subsequent PUSH is likely to cause another fault, which we will misinterpret as a double-fault.
*
* TODO: Throw a special JavaScript exception that cpu.js must intercept and quietly ignore.
*/
if (!EAFUNCS) {
this.opFlags &= ~(X86.OPFLAG.NOREAD | X86.OPFLAG.NOWRITE);