+ ; Save state RIP and RSP
+ lea rax, [rel .restore]
+ mov [rcx], rax
+ mov [rsi], rsp
+
+ ; Change CR3 if requested
+ test r8, r8
+ jz .setState
+ mov cr3, r8
+
+ ; Make sure the stack is valid before jumping
+ invlpg [rdi]
+ invlpg [rdi+0x1000]
+
+ ; Go to new state
+.setState:
+ mov rsp, rdi
+ jmp rdx
+
+ ; Restore point for saved state
+.restore:
+ POP_GPR
+ xor eax, eax ; Return zero
+ ret
+
+; vim: ft=nasm