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[NTVDM]

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Write a proper exception filter for the emulated CPU. Allows to:
- handle memory access exceptions inside the virtual memory space (happens when a VDD installs a memory hook on a memory region and a DOS app tries to read/write inside this region);
- detect NTVDM bugs (if during emulation one tries to read/write in invalid memory areas). This should unveils at least 1 bug in the DOS device emulation, when running 386TO486.COM inside NTVDM.

svn path=/trunk/; revision=66897
This commit is contained in:
Hermès Bélusca-Maïto 2015-03-26 01:46:27 +00:00
parent 8c77dacbfe
commit 2188c7a30c
1 changed files with 54 additions and 15 deletions
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69
reactos/subsystems/mvdm/ntvdm/cpu/cpu.c
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@ -112,10 +112,60 @@ VOID CpuStep(VOID)
Fast486StepInto(&EmulatorContext);
}
LONG CpuExceptionFilter(IN PEXCEPTION_POINTERS ExceptionInfo)
{
/* Get the exception record */
PEXCEPTION_RECORD ExceptionRecord = ExceptionInfo->ExceptionRecord;
switch (ExceptionRecord->ExceptionCode)
{
/* We only handle access violations so far */
case EXCEPTION_ACCESS_VIOLATION:
{
/* Retrieve the address to which a read or write attempt was made */
ULONG_PTR Pointer = ExceptionRecord->ExceptionInformation[1];
/*
* Check whether the access exception was done inside the virtual memory space
* (caused by an emulated app) or outside (casued by a bug in ourselves).
*/
if ((ULONG_PTR)Pointer < (ULONG_PTR)BaseAddress ||
(ULONG_PTR)Pointer > (ULONG_PTR)BaseAddress + MAX_ADDRESS)
{
DPRINT1("NTVDM: Access violation at 0x%p outside the virtual memory space!\n", Pointer);
return EXCEPTION_CONTINUE_SEARCH;
}
/* We are good to go. Dispatch to our memory handlers. */
{
BOOLEAN Writing = (ExceptionRecord->ExceptionInformation[0] == 1);
ULONG FaultAddress = (ULONG)PHYS_TO_REAL(Pointer);
/* Fix the CPU state */
Fast486Rewind(&EmulatorContext);
/* Call the handler */
MemExceptionHandler(FaultAddress, Writing);
}
// /* Continue executing the exception handler */
// return EXCEPTION_EXECUTE_HANDLER;
return EXCEPTION_CONTINUE_EXECUTION;
}
default:
{
DPRINT1("NTVDM: Exception 0x%08lx not handled!\n", ExceptionRecord->ExceptionCode);
break;
}
}
/* Continue to search for a handler */
return EXCEPTION_CONTINUE_SEARCH;
}
VOID CpuSimulate(VOID)
{
EXCEPTION_RECORD LocalExceptionRecord;
if (CpuCallLevel > MaxCpuCallLevel)
{
DisplayMessage(L"Too many CPU levels of recursion (%d, expected maximum %d)",
@ -135,20 +185,9 @@ VOID CpuSimulate(VOID)
{
while (VdmRunning && CpuRunning) ClockUpdate();
}
_SEH2_EXCEPT(LocalExceptionRecord = *_SEH2_GetExceptionInformation()->ExceptionRecord,
EXCEPTION_EXECUTE_HANDLER)
_SEH2_EXCEPT(CpuExceptionFilter(_SEH2_GetExceptionInformation()))
{
BOOLEAN Writing = (LocalExceptionRecord.ExceptionInformation[0] == 1);
ULONG FaultAddress = (ULONG)PHYS_TO_REAL(LocalExceptionRecord.ExceptionInformation[1]);
/* Make sure this was an access violation */
ASSERT(LocalExceptionRecord.ExceptionCode == EXCEPTION_ACCESS_VIOLATION);
/* Fix the CPU state */
Fast486Rewind(&EmulatorContext);
/* Call the handler */
MemExceptionHandler(FaultAddress, Writing);
DPRINT1("VDM exception handler called\n");
}
_SEH2_END;
}