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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));

70
tests/pc/80386/test386.nasm
View file

@ -107,6 +107,9 @@ DSEG_PROT16 equ 0x0018
DSEG_PROT32 equ 0x0020
SSEG_PROT32 equ 0x0028
;
; We set our exception handlers at fixed addresses to simplify interrupt gate descriptor initialization.
;
OFF_INTDIVERR equ 0xe000
;
@ -223,6 +226,10 @@ addrIDT:dw myIDTEnd - myIDT - 1 ; 16-bit limit of myIDT
myIDT: defGate CSEG_PROT32,OFF_INTDIVERR
myIDTEnd:
addrIDTReal:
dw 0x3FF ; 16-bit limit of real-mode IDT
dd 0x00000000 ; 32-bit base address of real-mode IDT
initGDT:
%ifdef RAM_GDT
set edi,RAM_GDT
@ -746,7 +753,8 @@ printVal:
TYPE_ARITH equ 0
TYPE_ARITH1 equ 1
TYPE_LOGIC equ 2
TYPE_MULDIV equ 3
TYPE_MULTIPLY equ 3
TYPE_DIVIDE equ 4
SIZE_BYTE equ 0
SIZE_SHORT equ 1
@ -816,18 +824,32 @@ tableOps:
defOp "DEC",dec,al,none,none,TYPE_ARITH1
defOp "DEC",dec,ax,none,none,TYPE_ARITH1
defOp "DEC",dec,eax,none,none,TYPE_ARITH1
defOp "IMULA",imul,dl,none,none,TYPE_MULDIV
defOp "IMULA",imul,dx,none,none,TYPE_MULDIV
defOp "IMULA",imul,edx,none,none,TYPE_MULDIV
defOp "IMUL",imul,ax,dx,none,TYPE_MULDIV
defOp "IMUL",imul,eax,edx,none,TYPE_MULDIV
defOp "IMUL8",imul,ax,dx,0x77,TYPE_ARITH1
defOp "IMUL8",imul,ax,dx,-0x77,TYPE_ARITH1
defOp "IMUL8",imul,eax,edx,0x77,TYPE_ARITH1
defOp "IMUL8",imul,eax,edx,-0x77,TYPE_ARITH1
defOp "IMUL16",imul,ax,0x777,none,TYPE_ARITH1
defOp "IMUL32",imul,eax,0x777777,none,TYPE_ARITH1
defOp "IDIVA",idiv,dl,none,none,TYPE_MULDIV
defOp "MULA",mul,dl,none,none,TYPE_MULTIPLY
defOp "MULA",mul,dx,none,none,TYPE_MULTIPLY
defOp "MULA",mul,edx,none,none,TYPE_MULTIPLY
defOp "IMULA",imul,dl,none,none,TYPE_MULTIPLY
defOp "IMULA",imul,dx,none,none,TYPE_MULTIPLY
defOp "IMULA",imul,edx,none,none,TYPE_MULTIPLY
defOp "IMUL",imul,ax,dx,none,TYPE_MULTIPLY
defOp "IMUL",imul,eax,edx,none,TYPE_MULTIPLY
defOp "IMUL8",imul,ax,dx,0x77,TYPE_MULTIPLY
defOp "IMUL8",imul,ax,dx,-0x77,TYPE_MULTIPLY
defOp "IMUL8",imul,eax,edx,0x77,TYPE_MULTIPLY
defOp "IMUL8",imul,eax,edx,-0x77,TYPE_MULTIPLY
defOp "IMUL16",imul,ax,0x777,none,TYPE_MULTIPLY
defOp "IMUL32",imul,eax,0x777777,none,TYPE_MULTIPLY
defOp "DIVDL",div,dl,none,none,TYPE_DIVIDE
defOp "DIVDX",div,dx,none,none,TYPE_DIVIDE
defOp "DIVEDX",div,edx,none,none,TYPE_DIVIDE
defOp "DIVAL",div,al,none,none,TYPE_DIVIDE
defOp "DIVAX",div,ax,none,none,TYPE_DIVIDE
defOp "DIVEAX",div,eax,none,none,TYPE_DIVIDE
defOp "IDIVDL",idiv,dl,none,none,TYPE_DIVIDE
defOp "IDIVDX",idiv,dx,none,none,TYPE_DIVIDE
defOp "IDIVEDX",idiv,edx,none,none,TYPE_DIVIDE
defOp "IDIVAL",idiv,al,none,none,TYPE_DIVIDE
defOp "IDIVAX",idiv,ax,none,none,TYPE_DIVIDE
defOp "IDIVEAX",idiv,eax,none,none,TYPE_DIVIDE
db 0
align 4
@ -836,7 +858,8 @@ typeMasks:
dd PS_ARITH
dd PS_ARITH
dd PS_LOGIC
dd PS_MULDIV
dd PS_MULTIPLY
dd PS_DIVIDE
arithValues:
.bvals: dd 0x00,0x01,0x02,0x7E,0x7F,0x80,0x81,0xFE,0xFF
@ -881,7 +904,14 @@ typeValues:
dd ARITH_BYTES+ARITH_WORDS+ARITH_DWORDS,arithValues,ARITH_BYTES+ARITH_WORDS+ARITH_DWORDS,arithValues
dd 0,0,0,0
;
; Values for TYPE_MULDIV (a superset of ARITH values)
; Values for TYPE_MULTIPLY (a superset of ARITH values)
;
dd MULDIV_BYTES,muldivValues,MULDIV_BYTES,muldivValues
dd MULDIV_BYTES+MULDIV_WORDS,muldivValues,MULDIV_BYTES+MULDIV_WORDS,muldivValues
dd MULDIV_BYTES+MULDIV_WORDS+MULDIV_DWORDS,muldivValues,MULDIV_BYTES+MULDIV_WORDS+MULDIV_DWORDS,muldivValues
dd 0,0,0,0
;
; Values for TYPE_DIVIDE
;
dd MULDIV_BYTES,muldivValues,MULDIV_BYTES,muldivValues
dd MULDIV_BYTES+MULDIV_WORDS,muldivValues,MULDIV_BYTES+MULDIV_WORDS,muldivValues
@ -899,8 +929,8 @@ intDivErr:
pop esi
;
; It's rather annoying that the 80386 treats #DE as a fault rather than a trap, leaving CS:EIP pointing to the
; faulting instruction. So we must "patch" the EIP on the stack to point to a RET; it's easier to use our own RET
; rather than figuring out how long the DIV instruction is.
; faulting instruction instead of the RET we conveniently placed after it. So, instead of trying to calculate where
; that RET is, we simply set EIP on the stack to point to our own RET.
;
mov dword [esp],intDivRet
iretd
@ -914,14 +944,16 @@ doneProt:
%ifndef REAL32
;
; Return to real-mode now, after first loading CS with a 16-bit code segment
; Return to real-mode, after first resetting the IDTR and loading CS with a 16-bit code segment
;
o32 lidt [cs:addrIDTReal]
jmp CSEG_PROT16:toProt16
toProt16:
bits 16
%endif
goReal: mov eax,cr0
goReal:
mov eax,cr0
and eax,~(CR0_MSW_PE | CR0_PG) & 0xffffffff
mov cr0,eax
jmpReal:

3
tests/pc/inc/x86.inc
View file

@ -12,7 +12,8 @@ PS_DF equ 0x0400
PS_OF equ 0x0800
PS_ARITH equ (PS_CF | PS_PF | PS_AF | PS_ZF | PS_SF | PS_OF)
PS_LOGIC equ (PS_CF | PS_PF | PS_ZF | PS_SF | PS_OF)
PS_MULDIV equ (PS_CF | PS_OF)
PS_MULTIPLY equ (PS_CF | PS_OF) ; only CF and OF are "defined" following MUL or IMUL
PS_DIVIDE equ 0 ; none of the Processor Status flags are "defined" following DIV or IDIV
CR0_MSW_PE equ 0x0001
CR0_PG equ 0x80000000 ; set if paging enabled