[NTOS:KE/x64] Implement KiSetTrapContext

KiSetTrapContext is an asm wrapper around RtlSetUnwindContext, which first stores an exception frame to assure that all non-volatile registers were put on the stack, then calls RtlSetUnwindContext to update their first saving positions on the stack and finally restore the exception frame to potentially load any updated registers, that haven't been saved elsewhere on the stack.

sdk/include/asm/ksamd64.template.h

@@ -1071,3 +1071,5 @@ OFFSET(KINTERRUPT_DispatchCount, KINTERRUPT, DispatchCount),
 OFFSET(KINTERRUPT_TrapFrame, KINTERRUPT, TrapFrame),
 OFFSET(KINTERRUPT_DispatchCode, KINTERRUPT, DispatchCode),
 
+HEADER("Misc definitions"),
+CONSTANT(MAX_SYSCALL_PARAM_SIZE),

sdk/include/ndk/amd64/asm.h

@@ -254,6 +254,9 @@ Author:
 #define CR0_CD                                  HEX(40000000)
 #define CR0_PG                                  HEX(80000000)
 
+/* Number of bytes reserved for syscall parameters */
+#define MAX_SYSCALL_PARAM_SIZE (16 * 8)
+
 #ifdef _ASM_
 //
 // CR4