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Make sure real-mode CS:IP changes never signal a stack switch

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This commit is contained in:
Jeff Parsons 2015-07-15 18:53:56 -07:00
commit d45f3174f6
4 changed files with 39 additions and 23 deletions
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11
modules/pcjs/lib/x86func.js
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@ -2147,9 +2147,18 @@ X86.fnRETF = function RETF(n)
var newIP = this.popWord();
var newCS = this.popWord();
if (DEBUG) this.printMessage(" returning to " + str.toHex(newCS, 4) + ':' + str.toHex(newIP, this.dataSize << 1), this.bitsMessage, true);
n <<= (this.dataSize >> 2);
if (n) this.setSP(this.getSP() + n); // TODO: optimize
if (this.setCSIP(newIP, newCS, false)) {
if (this.setCSIP(newIP, newCS, false)) { // returns true if a stack switch occurred
/*
* Fool me once, shame on... whatever. If setCSIP() indicates a stack switch occurred,
* make sure we're in protected mode, because automatic stack switches can't occur in real mode,
* and adjusting SP again under those circumstances will likely cause great harm.
*/
this.assert(!!(this.regCR0 & X86.CR0.MSW.PE));
if (n) this.setSP(this.getSP() + n); // TODO: optimize
/*
* As per Intel documentation: "If any of [the DS or ES] registers refer to segments whose DPL is