PspGetBaseTrapFrame(x64)

typedef struct _KERNEL_STACK_SEGMENT
{
	ULONG_PTR StackBase;
	ULONG_PTR StackLimit;
	ULONG_PTR KernelStack;
	ULONG_PTR InitialStack;
	ULONG_PTR ActualLimit;
} KERNEL_STACK_SEGMENT, *PKERNEL_STACK_SEGMENT;
typedef struct _KERNEL_STACK_CONTROL
{
	union {
		XMM_SAVE_AREA32 XmmSaveArea;
		struct {
			UCHAR Fill[sizeof(XMM_SAVE_AREA32) - 2 * sizeof(KERNEL_STACK_SEGMENT)];
			KERNEL_STACK_SEGMENT Current;
			KERNEL_STACK_SEGMENT Previous;
		};
	};

} KERNEL_STACK_CONTROL, *PKERNEL_STACK_CONTROL;
typedef struct _KTHREAD {
	DISPATCHER_HEADER Header;
	LIST_ENTRY MutantListHead;
	PVOID InitialStack;
	PVOID StackLimit;
	PVOID KernelStack;
} KTHREAD, *PKTHREAD, *PRKTHREAD;
typedef struct _ETHREAD {
	KTHREAD Tcb;
} ETHREAD, *PETHREAD;

#define KERNEL_STACK_CONTROL_LENGTH sizeof(KERNEL_STACK_CONTROL)
#define KTRAP_FRAME_LENGTH sizeof(KTRAP_FRAME)

FORCEINLINE PKTRAP_FRAME PspGetBaseTrapFrame(PETHREAD Thread)
{
	ULONG64 InitialStack;
	PKERNEL_STACK_CONTROL StackControl;

	InitialStack = (ULONG64)Thread->Tcb.InitialStack;
	StackControl = (PKERNEL_STACK_CONTROL)InitialStack;
	while (StackControl->Previous.StackBase != 0)
	{
		InitialStack = StackControl->Previous.InitialStack;
		StackControl = (PKERNEL_STACK_CONTROL)InitialStack;
	}
	return (PKTRAP_FRAME)(InitialStack - KTRAP_FRAME_LENGTH);
}