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i386: Prevent page faults when returning to same privilege and unmapped pages are above the stack. Windows 95 boots now. [Carl]

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This commit is contained in:
mahlemiut 2012-02-24 00:40:48 +00:00
parent c62d5a2d70
commit 4cedc79e43
1 changed files with 38 additions and 16 deletions
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54
src/emu/cpu/i386/i386.c
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@ -1915,7 +1915,6 @@ static void i386_protected_mode_call(i386_state *cpustate, UINT16 seg, UINT32 of
static void i386_protected_mode_retf(i386_state* cpustate, UINT8 count, UINT8 operand32)
{
UINT32 newCS, newEIP;
UINT32 newSS, newESP; // when changing privilege
I386_SREG desc;
UINT8 CPL, RPL, DPL;
@ -1925,17 +1924,11 @@ static void i386_protected_mode_retf(i386_state* cpustate, UINT8 count, UINT8 op
{
newEIP = READ16(cpustate, ea) & 0xffff;
newCS = READ16(cpustate, ea+2) & 0xffff;
ea += count+4;
newESP = READ16(cpustate, ea) & 0xffff;
newSS = READ16(cpustate, ea+2) & 0xffff;
}
else
{
newEIP = READ32(cpustate, ea);
newCS = READ32(cpustate, ea+4) & 0xffff;
ea += count+8;
newESP = READ32(cpustate, ea);
newSS = READ32(cpustate, ea+4) & 0xffff;
}
memset(&desc, 0, sizeof(desc));
@ -2031,6 +2024,7 @@ static void i386_protected_mode_retf(i386_state* cpustate, UINT8 count, UINT8 op
}
else if(RPL > CPL)
{
UINT32 newSS, newESP; // when changing privilege
/* outer privilege level */
if(operand32 == 0)
{
@ -2050,7 +2044,6 @@ static void i386_protected_mode_retf(i386_state* cpustate, UINT8 count, UINT8 op
FAULT(FAULT_SS,0)
}
}
/* Check CS selector and descriptor */
if((newCS & ~0x03) == 0)
{
@ -2104,6 +2097,20 @@ static void i386_protected_mode_retf(i386_state* cpustate, UINT8 count, UINT8 op
logerror("RETF: EIP is past return CS segment limit.\n");
FAULT(FAULT_GP,0)
}
if(operand32 == 0)
{
ea += count+4;
newESP = READ16(cpustate, ea) & 0xffff;
newSS = READ16(cpustate, ea+2) & 0xffff;
}
else
{
ea += count+8;
newESP = READ32(cpustate, ea);
newSS = READ32(cpustate, ea+4) & 0xffff;
}
/* Check SS selector and descriptor */
desc.selector = newSS;
i386_load_protected_mode_segment(cpustate,&desc);
@ -2191,16 +2198,12 @@ static void i386_protected_mode_iret(i386_state* cpustate, int operand32)
newEIP = READ16(cpustate, ea) & 0xffff;
newCS = READ16(cpustate, ea+2) & 0xffff;
newflags = READ16(cpustate, ea+4) & 0xffff;
newESP = READ16(cpustate, ea+6) & 0xffff;
newSS = READ16(cpustate, ea+8) & 0xffff;
}
else
{
newEIP = READ32(cpustate, ea);
newCS = READ32(cpustate, ea+4) & 0xffff;
newflags = READ32(cpustate, ea+8);
newESP = READ32(cpustate, ea+12);
newSS = READ32(cpustate, ea+16) & 0xffff;
}
if(V8086_MODE)
@ -2271,6 +2274,16 @@ static void i386_protected_mode_iret(i386_state* cpustate, int operand32)
if(newflags & 0x00020000) // if returning to virtual 8086 mode
{
// UINT8 SSRPL,SSDPL;
if(operand32 == 0)
{
newESP = READ16(cpustate, ea+6) & 0xffff;
newSS = READ16(cpustate, ea+8) & 0xffff;
}
else
{
newESP = READ32(cpustate, ea+12);
newSS = READ32(cpustate, ea+16) & 0xffff;
}
memset(&desc, 0, sizeof(desc));
desc.selector = newCS;
i386_load_protected_mode_segment(cpustate,&desc);
@ -2547,16 +2560,12 @@ static void i386_protected_mode_iret(i386_state* cpustate, int operand32)
}
else if(RPL > CPL)
{
I386_SREG stack;
/* return to outer privilege level */
memset(&desc, 0, sizeof(desc));
desc.selector = newCS;
i386_load_protected_mode_segment(cpustate,&desc);
DPL = (desc.flags >> 5) & 0x03; // descriptor privilege level
RPL = newCS & 0x03;
memset(&stack, 0, sizeof(stack));
stack.selector = newSS;
i386_load_protected_mode_segment(cpustate,&stack);
if(operand32 == 0)
{
UINT32 offset = (STACK_32BIT ? REG32(ESP) : REG16(SP));
@ -2625,6 +2634,19 @@ static void i386_protected_mode_iret(i386_state* cpustate, int operand32)
}
/* Check SS selector and descriptor */
if(operand32 == 0)
{
newESP = READ16(cpustate, ea+6) & 0xffff;
newSS = READ16(cpustate, ea+8) & 0xffff;
}
else
{
newESP = READ32(cpustate, ea+12);
newSS = READ32(cpustate, ea+16) & 0xffff;
}
memset(&stack, 0, sizeof(stack));
stack.selector = newSS;
i386_load_protected_mode_segment(cpustate,&stack);
DPL = (stack.flags >> 5) & 0x03;
if((newSS & ~0x03) == 0)
{