/**
* Capture a stack backtrace and optionally use the passed in exception pointers.
*
* @param BackTrace [out] Pointer to array to take backtrace
* @param MaxDepth Entries in BackTrace array
* @param Context Optional thread context information
*/
void FWindowsPlatformStackWalk::CaptureStackBackTrace( uint64* BackTrace, uint32 MaxDepth, void* Context )
{
// Make sure we have place to store the information before we go through the process of raising
// an exception and handling it.
if (BackTrace == NULL || MaxDepth == 0)
{
return;
}
if (Context)
{
CaptureStackTraceHelper(BackTrace, MaxDepth, (CONTEXT*)Context);
}
else
{
#if USE_FAST_STACKTRACE
if (!GMaxCallstackDepthInitialized)
{
DetermineMaxCallstackDepth();
}
PVOID WinBackTrace[MAX_CALLSTACK_DEPTH];
uint16 NumFrames = RtlCaptureStackBackTrace(0, FMath::Min<ULONG>(GMaxCallstackDepth, MaxDepth), WinBackTrace, NULL);
for (uint16 FrameIndex = 0; FrameIndex < NumFrames; ++FrameIndex)
{
BackTrace[FrameIndex] = (uint64)WinBackTrace[FrameIndex];
}
while (NumFrames < MaxDepth)
{
BackTrace[NumFrames++] = 0;
}
#elif USE_SLOW_STACKTRACE
// NOTE: Make sure to enable Stack Frame pointers: bOmitFramePointers = false, or /Oy-
// If GStackWalkingInitialized is true, traces will work anyway but will be much slower.
if (!GStackWalkingInitialized)
{
InitStackWalking();
}
CONTEXT HelperContext;
RtlCaptureContext(&HelperContext);
// Capture the back trace.
CaptureStackTraceHelper(BackTrace, MaxDepth, &HelperContext);
#elif PLATFORM_64BITS
// Raise an exception so CaptureStackBackTraceHelper has access to context record.
__try
{
RaiseException(0, // Application-defined exception code.
0, // Zero indicates continuable exception.
0, // Number of arguments in args array (ignored if args is NULL)
NULL); // Array of arguments
}
// Capture the back trace.
__except (CaptureStackTraceHelper(BackTrace, MaxDepth, (GetExceptionInformation())->ContextRecord))
{
}
#else
// Use a bit of inline assembly to capture the information relevant to stack walking which is
// basically EIP and EBP.
CONTEXT HelperContext;
memset(&HelperContext, 0, sizeof(CONTEXT));
HelperContext.ContextFlags = CONTEXT_FULL;
// Use a fake function call to pop the return address and retrieve EIP.
__asm
{
call FakeFunctionCall
FakeFunctionCall :
pop eax
mov HelperContext.Eip, eax
mov HelperContext.Ebp, ebp
mov HelperContext.Esp, esp
}
// Capture the back trace.
CaptureStackTraceHelper(BackTrace, MaxDepth, &HelperContext);
#endif
}
}
void PlatformStack::CaptureStackBackTrace(uint64* backTrace, uint32 maxDepth, void* context)
{
if (backTrace == NULL || maxDepth == 0)
{
return;
}
if (context)
{
CaptureStackTraceHelper(backTrace, maxDepth, (CONTEXT*)context);
}
else
{
#if USE_FAST_STACKTRACE
//if (!GMaxCallstackDepthInitialized)
//{
// DetermineMaxCallstackDepth();
//}
PVOID winBackTrace[MAX_CALLSTACK_DEPTH];
uint16 numFrames = RtlCaptureStackBackTrace(0, maxDepth, winBackTrace, NULL);
for (uint16 frameIndex = 0; frameIndex < numFrames; ++frameIndex)
{
backTrace[frameIndex] = (uint64)winBackTrace[frameIndex];
}
while (numFrames < maxDepth)
{
backTrace[numFrames++] = 0;
}
#elif USE_SLOW_STACKTRACE
InitSysStack();
CONTEXT helperContext;
RtlCaptureContext(&helperContext);
CaptureStackTraceHelper(backTrace, maxDepth, &helperContext);
#elif _WIN64
// Raise an exception so CaptureStackBackTraceHelper has access to context record.
__try
{
RaiseException(0, // Application-defined exception code.
0, // Zero indicates continuable exception.
0, // Number of arguments in args array (ignored if args is NULL)
NULL); // Array of arguments
}
// Capture the back trace.
__except (CaptureStackTraceHelper(backTrace, maxDepth, (GetExceptionInformation())->ContextRecord))
{
}
#else
// Use a bit of inline assembly to capture the information relevant to stack walking which is
// basically EIP and EBP.
CONTEXT HelperContext;
memset(&HelperContext, 0, sizeof(CONTEXT));
HelperContext.ContextFlags = CONTEXT_FULL;
// Use a fake function call to pop the return address and retrieve EIP.
__asm
{
call FakeFunctionCall
FakeFunctionCall :
pop eax
mov HelperContext.Eip, eax
mov HelperContext.Ebp, ebp
mov HelperContext.Esp, esp
}
// Capture the back trace.
CaptureStackTraceHelper(backTrace, maxDepth, &HelperContext);
#endif
}
}
