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reactos/sdk/lib/fast486/common.c

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/*
* Fast486 386/486 CPU Emulation Library
* common.c
*
* Copyright (C) 2015 Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/* INCLUDES *******************************************************************/
#include <windef.h>
// #define NDEBUG
#include <debug.h>
#include <fast486.h>
#include "common.h"
/* PUBLIC FUNCTIONS ***********************************************************/
BOOLEAN
FASTCALL
Fast486ReadMemory(PFAST486_STATE State,
FAST486_SEG_REGS SegmentReg,
ULONG Offset,
BOOLEAN InstFetch,
PVOID Buffer,
ULONG Size)
{
ULONG LinearAddress;
PFAST486_SEG_REG CachedDescriptor;
FAST486_EXCEPTIONS Exception = SegmentReg != FAST486_REG_SS
? FAST486_EXCEPTION_GP : FAST486_EXCEPTION_SS;
ASSERT(SegmentReg < FAST486_NUM_SEG_REGS);
/* Get the cached descriptor */
CachedDescriptor = &State->SegmentRegs[SegmentReg];
if (InstFetch || CachedDescriptor->Executable || !CachedDescriptor->DirConf)
{
if ((Offset + Size - 1) > CachedDescriptor->Limit)
{
/* Read beyond limit */
Fast486Exception(State, Exception);
return FALSE;
}
}
else
{
if (Offset < CachedDescriptor->Limit)
{
/* Read beyond limit */
Fast486Exception(State, Exception);
return FALSE;
}
}
/* Check for protected mode */
if ((State->ControlRegisters[FAST486_REG_CR0] & FAST486_CR0_PE) && !State->Flags.Vm)
{
/* Privilege checks */
if (!CachedDescriptor->Present)
{
Fast486Exception(State, Exception);
return FALSE;
}
if ((!InstFetch && (CachedDescriptor->Rpl > CachedDescriptor->Dpl))
|| (Fast486GetCurrentPrivLevel(State) > CachedDescriptor->Dpl))
{
Fast486Exception(State, Exception);
return FALSE;
}
if (InstFetch)
{
if (!CachedDescriptor->Executable)
{
/* Data segment not executable */
Fast486Exception(State, Exception);
return FALSE;
}
}
else
{
if (CachedDescriptor->Executable && (!CachedDescriptor->ReadWrite))
{
/* Code segment not readable */
Fast486Exception(State, Exception);
return FALSE;
}
}
}
/* Find the linear address */
LinearAddress = CachedDescriptor->Base + Offset;
#ifndef FAST486_NO_PREFETCH
if (InstFetch && ((Offset + FAST486_CACHE_SIZE - 1) <= CachedDescriptor->Limit))
{
State->PrefetchAddress = LinearAddress;
if ((State->ControlRegisters[FAST486_REG_CR0] & FAST486_CR0_PG)
&& (PAGE_OFFSET(State->PrefetchAddress) > (FAST486_PAGE_SIZE - FAST486_CACHE_SIZE)))
{
/* We mustn't prefetch across a page boundary */
State->PrefetchAddress = PAGE_ALIGN(State->PrefetchAddress)
| (FAST486_PAGE_SIZE - FAST486_CACHE_SIZE);
if ((LinearAddress - State->PrefetchAddress + Size) >= FAST486_CACHE_SIZE)
{
/* We can't prefetch without possibly violating page permissions */
State->PrefetchValid = FALSE;
return Fast486ReadLinearMemory(State, LinearAddress, Buffer, Size, TRUE);
}
}
/* Prefetch */
if (Fast486ReadLinearMemory(State,
State->PrefetchAddress,
State->PrefetchCache,
FAST486_CACHE_SIZE,
TRUE))
{
State->PrefetchValid = TRUE;
RtlMoveMemory(Buffer,
&State->PrefetchCache[LinearAddress - State->PrefetchAddress],
Size);
return TRUE;
}
else
{
State->PrefetchValid = FALSE;
return FALSE;
}
}
else
#endif
{
/* Read from the linear address */
return Fast486ReadLinearMemory(State, LinearAddress, Buffer, Size, TRUE);
}
}
BOOLEAN
FASTCALL
Fast486WriteMemory(PFAST486_STATE State,
FAST486_SEG_REGS SegmentReg,
ULONG Offset,
PVOID Buffer,
ULONG Size)
{
ULONG LinearAddress;
PFAST486_SEG_REG CachedDescriptor;
FAST486_EXCEPTIONS Exception = SegmentReg != FAST486_REG_SS
? FAST486_EXCEPTION_GP : FAST486_EXCEPTION_SS;
ASSERT(SegmentReg < FAST486_NUM_SEG_REGS);
/* Get the cached descriptor */
CachedDescriptor = &State->SegmentRegs[SegmentReg];
if (CachedDescriptor->Executable || !CachedDescriptor->DirConf)
{
if ((Offset + Size - 1) > CachedDescriptor->Limit)
{
/* Write beyond limit */
Fast486Exception(State, Exception);
return FALSE;
}
}
else
{
if (Offset < CachedDescriptor->Limit)
{
/* Write beyond limit */
Fast486Exception(State, Exception);
return FALSE;
}
}
/* Check for protected mode */
if ((State->ControlRegisters[FAST486_REG_CR0] & FAST486_CR0_PE) && !State->Flags.Vm)
{
/* Privilege checks */
if (!CachedDescriptor->Present)
{
Fast486Exception(State, Exception);
return FALSE;
}
if ((CachedDescriptor->Rpl > CachedDescriptor->Dpl)
|| (Fast486GetCurrentPrivLevel(State) > CachedDescriptor->Dpl))
{
Fast486Exception(State, Exception);
return FALSE;
}
if (CachedDescriptor->Executable)
{
/* Code segment not writable */
Fast486Exception(State, Exception);
return FALSE;
}
else if (!CachedDescriptor->ReadWrite)
{
/* Data segment not writeable */
Fast486Exception(State, Exception);
return FALSE;
}
}
/* Find the linear address */
LinearAddress = CachedDescriptor->Base + Offset;
#ifndef FAST486_NO_PREFETCH
if (State->PrefetchValid
&& (LinearAddress >= State->PrefetchAddress)
&& ((LinearAddress + Size) <= (State->PrefetchAddress + FAST486_CACHE_SIZE)))
{
/* Update the prefetch */
RtlMoveMemory(&State->PrefetchCache[LinearAddress - State->PrefetchAddress],
Buffer,
min(Size, FAST486_CACHE_SIZE + State->PrefetchAddress - LinearAddress));
}
#endif
/* Write to the linear address */
return Fast486WriteLinearMemory(State, LinearAddress, Buffer, Size, TRUE);
}
static inline BOOLEAN
FASTCALL
Fast486GetIntVector(PFAST486_STATE State,
UCHAR Number,
PFAST486_IDT_ENTRY IdtEntry)
{
/* Check for protected mode */
if (State->ControlRegisters[FAST486_REG_CR0] & FAST486_CR0_PE)
{
/* Read from the IDT */
if (!Fast486ReadLinearMemory(State,
State->Idtr.Address
+ Number * sizeof(*IdtEntry),
IdtEntry,
sizeof(*IdtEntry),
FALSE))
{
/* Exception occurred */
return FALSE;
}
}
else
{
/* Read from the real-mode IVT */
ULONG FarPointer;
/* Paging is always disabled in real mode */
State->MemReadCallback(State,
State->Idtr.Address
+ Number * sizeof(FarPointer),
&FarPointer,
sizeof(FarPointer));
/* Fill a fake IDT entry */
IdtEntry->Offset = LOWORD(FarPointer);
IdtEntry->Selector = HIWORD(FarPointer);
IdtEntry->Zero = 0;
IdtEntry->Type = FAST486_IDT_INT_GATE;
IdtEntry->Storage = FALSE;
IdtEntry->Dpl = 0;
IdtEntry->Present = TRUE;
IdtEntry->OffsetHigh = 0;
}
return TRUE;
}
static inline BOOLEAN
FASTCALL
Fast486InterruptInternal(PFAST486_STATE State,
PFAST486_IDT_ENTRY IdtEntry,
BOOLEAN PushErrorCode,
ULONG ErrorCode)
{
BOOLEAN GateSize = (IdtEntry->Type == FAST486_IDT_INT_GATE_32) ||
(IdtEntry->Type == FAST486_IDT_TRAP_GATE_32);
USHORT OldCs = State->SegmentRegs[FAST486_REG_CS].Selector;
ULONG OldEip = State->InstPtr.Long;
ULONG OldFlags = State->Flags.Long;
UCHAR OldCpl = State->Cpl;
/* Check for protected mode */
if (State->ControlRegisters[FAST486_REG_CR0] & FAST486_CR0_PE)
{
USHORT OldSs = State->SegmentRegs[FAST486_REG_SS].Selector;
ULONG OldEsp = State->GeneralRegs[FAST486_REG_ESP].Long;
BOOLEAN OldVm = State->Flags.Vm;
if (IdtEntry->Type == FAST486_TASK_GATE_SIGNATURE)
{
/* Task call */
if (!Fast486TaskSwitch(State, FAST486_TASK_CALL, IdtEntry->Selector))
{
/* Exception occurred */
return FALSE;
}
goto Finish;
}
/* Check if the interrupt handler is more privileged or if we're in V86 mode */
if ((OldCpl > GET_SEGMENT_RPL(IdtEntry->Selector)) || State->Flags.Vm)
{
FAST486_TSS Tss;
PFAST486_LEGACY_TSS LegacyTss = (PFAST486_LEGACY_TSS)&Tss;
USHORT NewSs;
ULONG NewEsp;
/* Read the TSS */
if (!Fast486ReadLinearMemory(State,
State->TaskReg.Base,
&Tss,
State->TaskReg.Modern
? sizeof(FAST486_TSS) : sizeof(FAST486_LEGACY_TSS),
FALSE))
{
/* Exception occurred */
return FALSE;
}
/* Switch to the new privilege level */
State->Cpl = GET_SEGMENT_RPL(IdtEntry->Selector);
/* Clear the VM flag */
State->Flags.Vm = FALSE;
/* Check the new (higher) privilege level */
switch (State->Cpl)
{
case 0:
{
if (State->TaskReg.Modern)
{
NewSs = Tss.Ss0;
NewEsp = Tss.Esp0;
}
else
{
NewSs = LegacyTss->Ss0;
NewEsp = LegacyTss->Sp0;
}
break;
}
case 1:
{
if (State->TaskReg.Modern)
{
NewSs = Tss.Ss1;
NewEsp = Tss.Esp1;
}
else
{
NewSs = LegacyTss->Ss1;
NewEsp = LegacyTss->Sp1;
}
break;
}
case 2:
{
if (State->TaskReg.Modern)
{
NewSs = Tss.Ss2;
NewEsp = Tss.Esp2;
}
else
{
NewSs = LegacyTss->Ss2;
NewEsp = LegacyTss->Sp2;
}
break;
}
default:
{
/* Should never reach here! */
ASSERT(FALSE);
}
}
if (!Fast486LoadSegment(State, FAST486_REG_SS, NewSs))
{
/* Exception occurred */
return FALSE;
}
State->GeneralRegs[FAST486_REG_ESP].Long = NewEsp;
}
/* Load new CS */
if (!Fast486LoadSegment(State, FAST486_REG_CS, IdtEntry->Selector))
{
/* An exception occurred during the jump */
return FALSE;
}
if (GateSize)
{
/* 32-bit code segment, use EIP */
State->InstPtr.Long = MAKELONG(IdtEntry->Offset, IdtEntry->OffsetHigh);
}
else
{
/* 16-bit code segment, use IP */
State->InstPtr.LowWord = IdtEntry->Offset;
}
/* Clear NT */
State->Flags.Nt = FALSE;
if (OldVm)
{
/* Push GS, FS, DS and ES */
if (!Fast486StackPushInternal(State,
GateSize,
State->SegmentRegs[FAST486_REG_GS].Selector))
{
return FALSE;
}
if (!Fast486StackPushInternal(State,
GateSize,
State->SegmentRegs[FAST486_REG_FS].Selector))
{
return FALSE;
}
if (!Fast486StackPushInternal(State,
GateSize,
State->SegmentRegs[FAST486_REG_DS].Selector))
{
return FALSE;
}
if (!Fast486StackPushInternal(State,
GateSize,
State->SegmentRegs[FAST486_REG_ES].Selector))
{
return FALSE;
}
/* Now load them with NULL selectors, since they are useless in protected mode */
if (!Fast486LoadSegment(State, FAST486_REG_GS, 0)) return FALSE;
if (!Fast486LoadSegment(State, FAST486_REG_FS, 0)) return FALSE;
if (!Fast486LoadSegment(State, FAST486_REG_DS, 0)) return FALSE;
if (!Fast486LoadSegment(State, FAST486_REG_ES, 0)) return FALSE;
}
/* Check if the interrupt handler is more privileged or we're in VM86 mode (again) */
if ((OldCpl > GET_SEGMENT_RPL(IdtEntry->Selector)) || OldVm)
{
/* Push SS selector */
if (!Fast486StackPushInternal(State, GateSize, OldSs)) return FALSE;
/* Push the stack pointer */
if (!Fast486StackPushInternal(State, GateSize, OldEsp)) return FALSE;
}
}
else
{
/* Load new CS */
if (!Fast486LoadSegment(State, FAST486_REG_CS, IdtEntry->Selector))
{
/* An exception occurred during the jump */
return FALSE;
}
/* Set the new IP */
State->InstPtr.LowWord = IdtEntry->Offset;
}
/* Push EFLAGS */
if (!Fast486StackPushInternal(State, GateSize, OldFlags)) return FALSE;
/* Push CS selector */
if (!Fast486StackPushInternal(State, GateSize, OldCs)) return FALSE;
/* Push the instruction pointer */
if (!Fast486StackPushInternal(State, GateSize, OldEip)) return FALSE;
Finish:
if (PushErrorCode)
{
/* Push the error code */
if (!Fast486StackPushInternal(State, GateSize, ErrorCode)) return FALSE;
}
if ((IdtEntry->Type == FAST486_IDT_INT_GATE)
|| (IdtEntry->Type == FAST486_IDT_INT_GATE_32))
{
/* Disable interrupts after a jump to an interrupt gate handler */
State->Flags.If = FALSE;
}
/* Clear TF */
State->Flags.Tf = FALSE;
return TRUE;
}
BOOLEAN
FASTCALL
Fast486PerformInterrupt(PFAST486_STATE State,
UCHAR Number)
{
FAST486_IDT_ENTRY IdtEntry;
/* Get the interrupt vector */
if (!Fast486GetIntVector(State, Number, &IdtEntry))
{
/* Exception occurred */
return FALSE;
}
/* Perform the interrupt */
if (!Fast486InterruptInternal(State, &IdtEntry, FALSE, 0))
{
/* Exception occurred */
return FALSE;
}
return TRUE;
}
VOID
FASTCALL
Fast486ExceptionWithErrorCode(PFAST486_STATE State,
FAST486_EXCEPTIONS ExceptionCode,
ULONG ErrorCode)
{
FAST486_IDT_ENTRY IdtEntry;
/* Increment the exception count */
State->ExceptionCount++;
/* Check if the exception occurred more than once */
if (State->ExceptionCount > 1)
{
/* Then this is a double fault */
ExceptionCode = FAST486_EXCEPTION_DF;
}
/* Check if this is a triple fault */
if (State->ExceptionCount == 3)
{
DPRINT("Fast486ExceptionWithErrorCode(%04X:%08X) -- Triple fault\n",
State->SegmentRegs[FAST486_REG_CS].Selector,
State->InstPtr.Long);
/* Reset the CPU */
Fast486Reset(State);
return;
}
/* Clear the prefix flags */
State->PrefixFlags = 0;
/* Restore the IP to the saved IP */
State->InstPtr = State->SavedInstPtr;
/* Restore the SP to the saved SP */
State->GeneralRegs[FAST486_REG_ESP] = State->SavedStackPtr;
/* Get the interrupt vector */
if (!Fast486GetIntVector(State, ExceptionCode, &IdtEntry))
{
/*
* If this function failed, that means Fast486Exception
* was called again, so just return in this case.
*/
return;
}
/* Perform the interrupt */
if (!Fast486InterruptInternal(State,
&IdtEntry,
EXCEPTION_HAS_ERROR_CODE(ExceptionCode)
&& (State->ControlRegisters[FAST486_REG_CR0] & FAST486_CR0_PE),
ErrorCode))
{
/*
* If this function failed, that means Fast486Exception
* was called again, so just return in this case.
*/
return;
}
/* Reset the exception count */
State->ExceptionCount = 0;
}
BOOLEAN
FASTCALL
Fast486TaskSwitch(PFAST486_STATE State, FAST486_TASK_SWITCH_TYPE Type, USHORT Selector)
{
ULONG NewTssAddress;
ULONG NewTssLimit;
FAST486_SYSTEM_DESCRIPTOR NewTssDescriptor;
FAST486_TSS OldTss;
PFAST486_LEGACY_TSS OldLegacyTss = (PFAST486_LEGACY_TSS)&OldTss;
FAST486_TSS NewTss;
PFAST486_LEGACY_TSS NewLegacyTss = (PFAST486_LEGACY_TSS)&NewTss;
USHORT NewLdtr, NewEs, NewCs, NewSs, NewDs;
if ((State->TaskReg.Modern && State->TaskReg.Limit < (sizeof(FAST486_TSS) - 1))
|| (!State->TaskReg.Modern && State->TaskReg.Limit < (sizeof(FAST486_LEGACY_TSS) - 1)))
{
/* Invalid task register limit */
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_TS, State->TaskReg.Selector);
return FALSE;
}
/* Read the old TSS */
if (!Fast486ReadLinearMemory(State,
State->TaskReg.Base,
&OldTss,
State->TaskReg.Modern
? sizeof(FAST486_TSS) : sizeof(FAST486_LEGACY_TSS),
FALSE))
{
/* Exception occurred */
return FALSE;
}
/* If this is a task return, use the linked previous selector */
if (Type == FAST486_TASK_RETURN)
{
if (State->TaskReg.Modern) Selector = LOWORD(OldTss.Link);
else Selector = OldLegacyTss->Link;
}
/* Make sure the entry exists in the GDT (not LDT!) */
if ((GET_SEGMENT_INDEX(Selector) == 0)
|| (Selector & SEGMENT_TABLE_INDICATOR)
|| GET_SEGMENT_INDEX(Selector) >= (State->Gdtr.Size + 1u))
{
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_TS, Selector);
return FALSE;
}
/* Get the TSS descriptor from the GDT */
if (!Fast486ReadLinearMemory(State,
State->Gdtr.Address + GET_SEGMENT_INDEX(Selector),
&NewTssDescriptor,
sizeof(NewTssDescriptor),
FALSE))
{
/* Exception occurred */
return FALSE;
}
if (!NewTssDescriptor.Present)
{
/* Incoming task TSS not present */
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_NP, Selector);
return FALSE;
}
/* Calculate the linear address of the new TSS */
NewTssAddress = NewTssDescriptor.Base;
NewTssAddress |= NewTssDescriptor.BaseMid << 16;
NewTssAddress |= NewTssDescriptor.BaseHigh << 24;
/* Calculate the limit of the new TSS */
NewTssLimit = NewTssDescriptor.Limit | (NewTssDescriptor.LimitHigh << 16);
if (NewTssDescriptor.Granularity)
{
NewTssLimit <<= 12;
NewTssLimit |= 0x00000FFF;
}
if (NewTssLimit < (sizeof(FAST486_TSS) - 1)
&& NewTssLimit != (sizeof(FAST486_LEGACY_TSS) - 1))
{
/* TSS limit invalid */
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_TS, Selector);
return FALSE;
}
/*
* The incoming task shouldn't be busy if we're executing it as a
* new task, and it should be busy if we're returning to it.
*/
if ((((NewTssDescriptor.Signature != FAST486_TSS_SIGNATURE)
&& (NewTssDescriptor.Signature != FAST486_TSS_16_SIGNATURE))
|| (Type == FAST486_TASK_RETURN))
&& (((NewTssDescriptor.Signature != FAST486_BUSY_TSS_SIGNATURE)
&& (NewTssDescriptor.Signature != FAST486_BUSY_TSS_16_SIGNATURE))
|| (Type != FAST486_TASK_RETURN)))
{
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_GP, Selector);
return FALSE;
}
/* Read the new TSS */
if (!Fast486ReadLinearMemory(State,
NewTssAddress,
&NewTss,
(NewTssDescriptor.Signature == FAST486_TSS_SIGNATURE)
|| (NewTssDescriptor.Signature == FAST486_BUSY_TSS_SIGNATURE)
? sizeof(FAST486_TSS) : sizeof(FAST486_LEGACY_TSS),
FALSE))
{
/* Exception occurred */
return FALSE;
}
if (Type != FAST486_TASK_CALL)
{
/* Clear the busy bit of the outgoing task */
FAST486_SYSTEM_DESCRIPTOR OldTssDescriptor;
if (!Fast486ReadLinearMemory(State,
State->Gdtr.Address
+ GET_SEGMENT_INDEX(State->TaskReg.Selector),
&OldTssDescriptor,
sizeof(OldTssDescriptor),
FALSE))
{
/* Exception occurred */
return FALSE;
}
OldTssDescriptor.Signature = FAST486_TSS_SIGNATURE;
if (!Fast486WriteLinearMemory(State,
State->Gdtr.Address
+ GET_SEGMENT_INDEX(State->TaskReg.Selector),
&OldTssDescriptor,
sizeof(OldTssDescriptor),
FALSE))
{
/* Exception occurred */
return FALSE;
}
}
else
{
/* Store the link */
if ((NewTssDescriptor.Signature == FAST486_TSS_SIGNATURE)
|| (NewTssDescriptor.Signature == FAST486_BUSY_TSS_SIGNATURE))
{
NewTss.Link = State->TaskReg.Selector;
/* Write back the new TSS link */
if (!Fast486WriteLinearMemory(State,
NewTssAddress,
&NewTss.Link,
sizeof(NewTss.Link),
FALSE))
{
/* Exception occurred */
return FALSE;
}
}
else
{
NewLegacyTss->Link = State->TaskReg.Selector;
/* Write back the new legacy TSS link */
if (!Fast486WriteLinearMemory(State,
NewTssAddress,
&NewLegacyTss->Link,
sizeof(NewLegacyTss->Link),
FALSE))
{
/* Exception occurred */
return FALSE;
}
}
}
/* Save the current task into the TSS */
if (State->TaskReg.Modern)
{
OldTss.Cr3 = State->ControlRegisters[FAST486_REG_CR3];
OldTss.Eip = State->InstPtr.Long;
OldTss.Eflags = State->Flags.Long;
OldTss.Eax = State->GeneralRegs[FAST486_REG_EAX].Long;
OldTss.Ecx = State->GeneralRegs[FAST486_REG_ECX].Long;
OldTss.Edx = State->GeneralRegs[FAST486_REG_EDX].Long;
OldTss.Ebx = State->GeneralRegs[FAST486_REG_EBX].Long;
OldTss.Esp = State->GeneralRegs[FAST486_REG_ESP].Long;
OldTss.Ebp = State->GeneralRegs[FAST486_REG_EBP].Long;
OldTss.Esi = State->GeneralRegs[FAST486_REG_ESI].Long;
OldTss.Edi = State->GeneralRegs[FAST486_REG_EDI].Long;
OldTss.Es = State->SegmentRegs[FAST486_REG_ES].Selector;
OldTss.Cs = State->SegmentRegs[FAST486_REG_CS].Selector;
OldTss.Ss = State->SegmentRegs[FAST486_REG_SS].Selector;
OldTss.Ds = State->SegmentRegs[FAST486_REG_DS].Selector;
OldTss.Fs = State->SegmentRegs[FAST486_REG_FS].Selector;
OldTss.Gs = State->SegmentRegs[FAST486_REG_GS].Selector;
OldTss.Ldtr = State->Ldtr.Selector;
}
else
{
OldLegacyTss->Ip = State->InstPtr.LowWord;
OldLegacyTss->Flags = State->Flags.LowWord;
OldLegacyTss->Ax = State->GeneralRegs[FAST486_REG_EAX].LowWord;
OldLegacyTss->Cx = State->GeneralRegs[FAST486_REG_ECX].LowWord;
OldLegacyTss->Dx = State->GeneralRegs[FAST486_REG_EDX].LowWord;
OldLegacyTss->Bx = State->GeneralRegs[FAST486_REG_EBX].LowWord;
OldLegacyTss->Sp = State->GeneralRegs[FAST486_REG_ESP].LowWord;
OldLegacyTss->Bp = State->GeneralRegs[FAST486_REG_EBP].LowWord;
OldLegacyTss->Si = State->GeneralRegs[FAST486_REG_ESI].LowWord;
OldLegacyTss->Di = State->GeneralRegs[FAST486_REG_EDI].LowWord;
OldLegacyTss->Es = State->SegmentRegs[FAST486_REG_ES].Selector;
OldLegacyTss->Cs = State->SegmentRegs[FAST486_REG_CS].Selector;
OldLegacyTss->Ss = State->SegmentRegs[FAST486_REG_SS].Selector;
OldLegacyTss->Ds = State->SegmentRegs[FAST486_REG_DS].Selector;
OldLegacyTss->Ldtr = State->Ldtr.Selector;
}
/* Write back the old TSS */
if (!Fast486WriteLinearMemory(State,
State->TaskReg.Base,
&OldTss,
State->TaskReg.Modern
? sizeof(FAST486_TSS) : sizeof(FAST486_LEGACY_TSS),
FALSE))
{
/* Exception occurred */
return FALSE;
}
/* Mark the new task as busy */
if (NewTssDescriptor.Signature == FAST486_TSS_SIGNATURE
|| NewTssDescriptor.Signature == FAST486_BUSY_TSS_SIGNATURE)
{
/* 32-bit TSS */
NewTssDescriptor.Signature = FAST486_BUSY_TSS_SIGNATURE;
}
else
{
/* 16-bit TSS */
NewTssDescriptor.Signature = FAST486_BUSY_TSS_16_SIGNATURE;
}
/* Write back the new TSS descriptor */
if (!Fast486WriteLinearMemory(State,
State->Gdtr.Address + GET_SEGMENT_INDEX(Selector),
&NewTssDescriptor,
sizeof(NewTssDescriptor),
FALSE))
{
/* Exception occurred */
return FALSE;
}
/* Set the task switch bit */
State->ControlRegisters[FAST486_REG_CR0] |= FAST486_CR0_TS;
/* Load the task register with the new values */
State->TaskReg.Selector = Selector;
State->TaskReg.Base = NewTssAddress;
State->TaskReg.Limit = NewTssLimit;
State->TaskReg.Modern = (NewTssDescriptor.Signature == FAST486_BUSY_TSS_SIGNATURE);
if (NewTssDescriptor.Signature == FAST486_BUSY_TSS_SIGNATURE)
{
/* Change the page directory */
State->ControlRegisters[FAST486_REG_CR3] = NewTss.Cr3;
}
/* Flush the TLB */
Fast486FlushTlb(State);
/* Update the CPL */
if (NewTssDescriptor.Signature == FAST486_BUSY_TSS_SIGNATURE)
{
State->Cpl = GET_SEGMENT_RPL(NewTss.Cs);
}
else
{
State->Cpl = GET_SEGMENT_RPL(NewLegacyTss->Cs);
}
#ifndef FAST486_NO_PREFETCH
/* Context switching invalidates the prefetch */
State->PrefetchValid = FALSE;
#endif
/* Load the registers */
if (NewTssDescriptor.Signature == FAST486_BUSY_TSS_SIGNATURE)
{
State->InstPtr.Long = State->SavedInstPtr.Long = NewTss.Eip;
State->Flags.Long = NewTss.Eflags;
State->GeneralRegs[FAST486_REG_EAX].Long = NewTss.Eax;
State->GeneralRegs[FAST486_REG_ECX].Long = NewTss.Ecx;
State->GeneralRegs[FAST486_REG_EDX].Long = NewTss.Edx;
State->GeneralRegs[FAST486_REG_EBX].Long = NewTss.Ebx;
State->GeneralRegs[FAST486_REG_EBP].Long = NewTss.Ebp;
State->GeneralRegs[FAST486_REG_ESI].Long = NewTss.Esi;
State->GeneralRegs[FAST486_REG_EDI].Long = NewTss.Edi;
NewEs = NewTss.Es;
NewCs = NewTss.Cs;
NewDs = NewTss.Ds;
NewLdtr = NewTss.Ldtr;
if (Type == FAST486_TASK_CALL && State->Cpl < 3)
{
switch (State->Cpl)
{
case 0:
{
State->GeneralRegs[FAST486_REG_ESP].Long = NewTss.Esp0;
NewSs = NewTss.Ss0;
break;
}
case 1:
{
State->GeneralRegs[FAST486_REG_ESP].Long = NewTss.Esp1;
NewSs = NewTss.Ss1;
break;
}
case 2:
{
State->GeneralRegs[FAST486_REG_ESP].Long = NewTss.Esp2;
NewSs = NewTss.Ss2;
break;
}
}
}
else
{
State->GeneralRegs[FAST486_REG_ESP].Long = NewTss.Esp;
NewSs = NewTss.Ss;
}
}
else
{
State->InstPtr.LowWord = State->SavedInstPtr.LowWord = NewLegacyTss->Ip;
State->Flags.LowWord = NewLegacyTss->Flags;
State->GeneralRegs[FAST486_REG_EAX].LowWord = NewLegacyTss->Ax;
State->GeneralRegs[FAST486_REG_ECX].LowWord = NewLegacyTss->Cx;
State->GeneralRegs[FAST486_REG_EDX].LowWord = NewLegacyTss->Dx;
State->GeneralRegs[FAST486_REG_EBX].LowWord = NewLegacyTss->Bx;
State->GeneralRegs[FAST486_REG_EBP].LowWord = NewLegacyTss->Bp;
State->GeneralRegs[FAST486_REG_ESI].LowWord = NewLegacyTss->Si;
State->GeneralRegs[FAST486_REG_EDI].LowWord = NewLegacyTss->Di;
NewEs = NewLegacyTss->Es;
NewCs = NewLegacyTss->Cs;
NewDs = NewLegacyTss->Ds;
NewLdtr = NewLegacyTss->Ldtr;
if (Type == FAST486_TASK_CALL && State->Cpl < 3)
{
switch (State->Cpl)
{
case 0:
{
State->GeneralRegs[FAST486_REG_ESP].Long = NewLegacyTss->Sp0;
NewSs = NewLegacyTss->Ss0;
break;
}
case 1:
{
State->GeneralRegs[FAST486_REG_ESP].Long = NewLegacyTss->Sp1;
NewSs = NewLegacyTss->Ss1;
break;
}
case 2:
{
State->GeneralRegs[FAST486_REG_ESP].Long = NewLegacyTss->Sp2;
NewSs = NewLegacyTss->Ss2;
break;
}
}
}
else
{
State->GeneralRegs[FAST486_REG_ESP].Long = NewLegacyTss->Sp;
NewSs = NewLegacyTss->Ss;
}
}
/* Set the NT flag if nesting */
if (Type == FAST486_TASK_CALL) State->Flags.Nt = TRUE;
if (GET_SEGMENT_INDEX(NewLdtr) != 0)
{
BOOLEAN Valid;
FAST486_SYSTEM_DESCRIPTOR GdtEntry;
if (NewLdtr & SEGMENT_TABLE_INDICATOR)
{
/* This selector doesn't point to the GDT */
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_TS, NewLdtr);
return FALSE;
}
if (!Fast486ReadDescriptorEntry(State, NewLdtr, &Valid, (PFAST486_GDT_ENTRY)&GdtEntry))
{
/* Exception occurred */
return FALSE;
}
if (!Valid)
{
/* Invalid selector */
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_TS, NewLdtr);
return FALSE;
}
if (GdtEntry.Signature != FAST486_LDT_SIGNATURE)
{
/* This is not an LDT descriptor */
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_TS, NewLdtr);
return FALSE;
}
if (!GdtEntry.Present)
{
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_TS, NewLdtr);
return FALSE;
}
/* Update the LDTR */
State->Ldtr.Selector = NewLdtr;
State->Ldtr.Base = GdtEntry.Base | (GdtEntry.BaseMid << 16) | (GdtEntry.BaseHigh << 24);
State->Ldtr.Limit = GdtEntry.Limit | (GdtEntry.LimitHigh << 16);
if (GdtEntry.Granularity)
{
State->Ldtr.Limit <<= 12;
State->Ldtr.Limit |= 0x00000FFF;
}
}
else
{
/* The LDT of this task is empty */
RtlZeroMemory(&State->Ldtr, sizeof(State->Ldtr));
}
/* Load the new segments */
if (!Fast486LoadSegmentInternal(State, FAST486_REG_CS, NewCs, FAST486_EXCEPTION_TS))
{
return FALSE;
}
if (!Fast486LoadSegmentInternal(State, FAST486_REG_SS, NewSs, FAST486_EXCEPTION_TS))
{
return FALSE;
}
if (!Fast486LoadSegmentInternal(State, FAST486_REG_ES, NewEs, FAST486_EXCEPTION_TS))
{
return FALSE;
}
if (!Fast486LoadSegmentInternal(State, FAST486_REG_DS, NewDs, FAST486_EXCEPTION_TS))
{
return FALSE;
}
if (NewTssDescriptor.Signature == FAST486_BUSY_TSS_SIGNATURE)
{
if (!Fast486LoadSegmentInternal(State,
FAST486_REG_FS,
NewTss.Fs,
FAST486_EXCEPTION_TS))
{
return FALSE;
}
if (!Fast486LoadSegmentInternal(State,
FAST486_REG_GS,
NewTss.Gs,
FAST486_EXCEPTION_TS))
{
return FALSE;
}
}
return TRUE;
}
BOOLEAN
FASTCALL
Fast486CallGate(PFAST486_STATE State,
PFAST486_CALL_GATE Gate,
BOOLEAN Call)
{
BOOLEAN Valid;
FAST486_GDT_ENTRY NewCodeSegment;
BOOLEAN GateSize = (Gate->Type == FAST486_CALL_GATE_SIGNATURE);
FAST486_TSS Tss;
PFAST486_LEGACY_TSS LegacyTss = (PFAST486_LEGACY_TSS)&Tss;
USHORT OldCs = State->SegmentRegs[FAST486_REG_CS].Selector;
ULONG OldEip = State->InstPtr.Long;
USHORT OldCpl = State->Cpl;
USHORT OldSs = State->SegmentRegs[FAST486_REG_SS].Selector;
ULONG OldEsp = State->GeneralRegs[FAST486_REG_ESP].Long;
ULONG ParamBuffer[32]; /* Maximum possible size - 32 DWORDs */
PULONG LongParams = (PULONG)ParamBuffer;
PUSHORT ShortParams = (PUSHORT)ParamBuffer;
if (!Gate->Selector)
{
/* The code segment is NULL */
Fast486Exception(State, FAST486_EXCEPTION_GP);
return FALSE;
}
if (!Fast486ReadDescriptorEntry(State, Gate->Selector, &Valid, &NewCodeSegment))
{
/* Exception occurred */
return FALSE;
}
if (!Valid || (NewCodeSegment.Dpl > Fast486GetCurrentPrivLevel(State)))
{
/* Code segment invalid */
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_GP, Gate->Selector);
return FALSE;
}
if (Call && Gate->ParamCount)
{
/* Read the parameters */
if (!Fast486ReadMemory(State,
FAST486_REG_SS,
OldEsp,
FALSE,
ParamBuffer,
Gate->ParamCount * (GateSize ? sizeof(ULONG) : sizeof(USHORT))))
{
/* Exception occurred */
return FALSE;
}
}
/* Check if the new code segment is more privileged */
if (NewCodeSegment.Dpl < OldCpl)
{
if (Call)
{
USHORT NewSs;
ULONG NewEsp;
/* Read the TSS */
if (!Fast486ReadLinearMemory(State,
State->TaskReg.Base,
&Tss,
State->TaskReg.Modern
? sizeof(FAST486_TSS) : sizeof(FAST486_LEGACY_TSS),
FALSE))
{
/* Exception occurred */
return FALSE;
}
/* Switch to the new privilege level */
State->Cpl = NewCodeSegment.Dpl;
/* Check the new (higher) privilege level */
switch (State->Cpl)
{
case 0:
{
if (State->TaskReg.Modern)
{
NewSs = Tss.Ss0;
NewEsp = Tss.Esp0;
}
else
{
NewSs = LegacyTss->Ss0;
NewEsp = LegacyTss->Sp0;
}
break;
}
case 1:
{
if (State->TaskReg.Modern)
{
NewSs = Tss.Ss1;
NewEsp = Tss.Esp1;
}
else
{
NewSs = LegacyTss->Ss1;
NewEsp = LegacyTss->Sp1;
}
break;
}
case 2:
{
if (State->TaskReg.Modern)
{
NewSs = Tss.Ss2;
NewEsp = Tss.Esp2;
}
else
{
NewSs = LegacyTss->Ss2;
NewEsp = LegacyTss->Sp2;
}
break;
}
default:
{
/* Should never reach here! */
ASSERT(FALSE);
}
}
if (!Fast486LoadSegment(State, FAST486_REG_SS, NewSs))
{
/* Exception occurred */
return FALSE;
}
State->GeneralRegs[FAST486_REG_ESP].Long = NewEsp;
}
else if (!NewCodeSegment.DirConf)
{
/* This is not allowed for jumps */
Fast486ExceptionWithErrorCode(State, FAST486_EXCEPTION_GP, Gate->Selector);
return FALSE;
}
}
/* Load new CS */
if (!Fast486LoadSegment(State, FAST486_REG_CS, Gate->Selector))
{
/* An exception occurred during the jump */
return FALSE;
}
/* Set the instruction pointer */
if (GateSize) State->InstPtr.Long = MAKELONG(Gate->Offset, Gate->OffsetHigh);
else State->InstPtr.Long = Gate->Offset;
if (Call)
{
INT i;
/* Check if the new code segment is more privileged (again) */
if (NewCodeSegment.Dpl < OldCpl)
{
/* Push SS selector */
if (!Fast486StackPushInternal(State, GateSize, OldSs)) return FALSE;
/* Push stack pointer */
if (!Fast486StackPushInternal(State, GateSize, OldEsp)) return FALSE;
}
/* Push the parameters in reverse order */
for (i = Gate->ParamCount - 1; i >= 0; i--)
{
if (!Fast486StackPushInternal(State,
GateSize,
GateSize ? LongParams[i] : ShortParams[i]))
{
/* Exception occurred */
return FALSE;
}
}
/* Push CS selector */
if (!Fast486StackPushInternal(State, GateSize, OldCs)) return FALSE;
/* Push the instruction pointer */
if (!Fast486StackPushInternal(State, GateSize, OldEip)) return FALSE;
}
return TRUE;
}
/* EOF */
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