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Make far calls restartable when they trigger a fault pushing the return address onto the stack

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This commit is contained in:
Jeff Parsons 2015-10-18 17:40:29 -07:00
commit b0ada4229d
4 changed files with 68 additions and 31 deletions
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1
modules/pcjs/lib/x86cpu.js
View file

@ -1397,6 +1397,7 @@ X86CPU.prototype.resetRegs = function()
* currently opLIP is updated prior to every instruction, but opLSP is updated only for instructions
* that read/write the stack (eg, RETF) and should otherwise remain set to X86.ADDR_INVALID.
*/
this.opCS = -1;
this.opLIP = this.opLSP = X86.ADDR_INVALID;
/*

25
modules/pcjs/lib/x86func.js
View file

@ -558,21 +558,20 @@ X86.fnCALLw = function(dst, src)
X86.fnCALLF = function(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.
* Since we always push the return address AFTER calling setCSIP(), and since either push could trigger
* fault (eg, segment fault, page fault, etc), we must not only snapshot regLSP into opLSP, but also the
* current CS into opCS, so that fnFault() can make this CALL restartable.
*/
this.opCS = this.getCS();
this.opLSP = this.regLSP;
var oldCS = this.getCS();
var oldIP = this.getIP();
var oldSize = (I386? this.sizeData : 2);
if (this.setCSIP(off, sel, true) != null) {
this.pushData(oldCS, oldSize);
this.pushData(this.opCS, oldSize);
this.pushData(oldIP, oldSize);
}
this.opLSP = X86.ADDR_INVALID;
this.opCS = -1;
};
/**
@ -768,7 +767,7 @@ X86.fnShr64 = function(dst)
*
* This sets regMDLo to dstHi:dstLo / src, and regMDHi to dstHi:dstLo % src; all inputs are treated as unsigned.
*
* If fMDset is not set, however, then there was a divide exception (ie, the divisor was either zero or too small).
* If fMDSet is not set, however, then there was a divide exception (ie, the divisor was either zero or too small).
*
* Refer to: http://lxr.linux.no/linux+v2.6.22/lib/div64.c
*
@ -799,8 +798,8 @@ X86.fnDIV32 = function(dstLo, dstHi, src)
result += bit;
}
X86.fnShr64(div);
bit >>>= 1;
} while (bit);
bit /= 2;
} while (bit >= 1);
this.assert(result <= 0xffffffff && !rem[1]);
@ -814,7 +813,7 @@ X86.fnDIV32 = function(dstLo, dstHi, src)
*
* This sets regMDLo to dstHi:dstLo / src, and regMDHi to dstHi:dstLo % src; all inputs are treated as signed.
*
* If fMDset is not set, however, then there was a divide exception (ie, the divisor was either zero or too small).
* If fMDSet is not set, however, then there was a divide exception (ie, the divisor was either zero or too small).
*
* Refer to: http://lxr.linux.no/linux+v2.6.22/lib/div64.c
*
@ -3980,6 +3979,10 @@ X86.fnFault = function(nFault, nError, nCycles, fHalt)
* the current instruction contains an OPERAND size override).
*/
this.resetSizes();
if (this.opCS != -1) {
this.setCS(this.opCS);
this.opCS = -1;
}
this.setIP(this.opLIP - this.segCS.base);
if (this.opLSP != X86.ADDR_INVALID) {
this.setSP((this.regESP & ~this.segSS.maskAddr) | (this.opLSP - this.segSS.base));