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v1.19.6: Improved restartability of stack-related instructions

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This commit is contained in:
Jeff Parsons 2015-09-14 16:53:57 -07:00
commit deeac4902d
174 changed files with 9030 additions and 1736 deletions
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49
modules/pcjs/lib/x86func.js
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@ -560,6 +560,13 @@ X86.fnCALLw = function CALLw(dst, src)
*/
X86.fnCALLF = function CALLF(off, sel)
{
/*
* Originally, we would snapshot regLSP into opLSP because setCSIP() could trigger a segment fault,
* but additionally, the stack segment could trigger either a segment fault or a page fault; indeed,
* any operation that performs multiple stack modifications must take this precaution and snapshot regLSP.
*/
this.opLSP = this.regLSP;
var oldCS = this.getCS();
var oldIP = this.getIP();
var oldSize = (I386? this.sizeData : 2);
@ -567,6 +574,8 @@ X86.fnCALLF = function CALLF(off, sel)
this.pushData(oldCS, oldSize);
this.pushData(oldIP, oldSize);
}
this.opLSP = X86.ADDR_INVALID;
};
/**
@ -582,9 +591,18 @@ X86.fnCALLFdw = function CALLFdw(dst, src)
if (this.regEA === X86.ADDR_INVALID) {
return X86.fnGRPUndefined.call(this, dst, src);
}
/*
* Originally, we would snapshot regLSP into opLSP because fnCALLF() could trigger a segment fault,
* but additionally, the stack segment could trigger either a segment fault or a page fault; indeed,
* any operation that performs multiple stack modifications must take this precaution and snapshot regLSP.
*/
this.opLSP = this.regLSP;
X86.fnCALLF.call(this, dst, this.getShort(this.regEA + this.sizeData));
this.nStepCycles -= this.cycleCounts.nOpCyclesCallDM;
this.opFlags |= X86.OPFLAG.NOWRITE;
this.opLSP = X86.ADDR_INVALID;
return dst;
};
@ -1444,7 +1462,9 @@ X86.fnINT = function INT(nIDT, nError, nCycles)
X86.fnIRET = function IRET()
{
/*
* As discussed in fnRETF(), we temporarily set opLSP around operations that fnFault() may need to restart.
* Originally, we would snapshot regLSP into opLSP because newCS could trigger a segment fault,
* but additionally, the stack segment could trigger either a segment fault or a page fault; indeed,
* any operation that performs multiple stack modifications must take this precaution and snapshot regLSP.
*/
this.opLSP = this.regLSP;
@ -1515,6 +1535,7 @@ X86.fnIRET = function IRET()
if (this.cIntReturn) this.checkIntReturn(this.regLIP);
}
}
this.opLSP = X86.ADDR_INVALID;
};
@ -2418,31 +2439,16 @@ X86.fnRCRd = function RCRd(dst, src)
* we may have switched to; setCSIP() returns true if a stack switch occurred, false if not, and null
* if an error occurred.
*
* Take a look at our counterpart, fnCALLF():
*
* if (this.setCSIP(off, sel, true) != null) {
* this.pushWord(oldCS);
* this.pushWord(oldIP);
* }
*
* That code is inherently restartable, because it doesn't modify the stack unless setCSIP() succeeds.
*
* Here, our task is a little more complicated, because 1) it's not convenient to defer our stack
* operations until AFTER setCSIP(); 2) we have to deal with an additional stack adjustment value (n);
* and 3) if setCSIP() triggers a fault (eg, NP_FAULT), fnFault() must be able to do the rewinding,
* which happens BEFORE setCSIP() returns.
*
* The current hack to make the stack "rewindable" involves copying regLSP to opLSP, similar to what we do
* for EIP (ie, by copying regLIP into opLIP prior to executing every opcode), so that fnFault() can rewind
* ESP as needed. And since I don't really want to snapshot more data inside the opcode loop, my compromise
* is to set opLSP only within instructions (like this one) that read/write the stack, and then reset opLSP
* back to X86.ADDR_INVALID when we're done.
*
* @this {X86CPU}
* @param {number} n
*/
X86.fnRETF = function RETF(n)
{
/*
* Originally, we would snapshot regLSP into opLSP because newCS could trigger a segment fault,
* but additionally, the stack segment could trigger either a segment fault or a page fault; indeed,
* any operation that performs multiple stack modifications must take this precaution and snapshot regLSP.
*/
this.opLSP = this.regLSP;
var newIP = this.popWord();
@ -2476,6 +2482,7 @@ X86.fnRETF = function RETF(n)
}
}
if (n == 2 && this.cIntReturn) this.checkIntReturn(this.regLIP);
this.opLSP = X86.ADDR_INVALID;
};