x86 stuff

arch/x86_64/include/bits/sched.h

@@ -37,6 +37,7 @@ struct arch_context {
 };
 
 #define ARCH_CTX_NUM  rax
+#define ARCH_CTX_SP   rsp
 #define ARCH_CTX_A0   rdi
 #define ARCH_CTX_A1   rsi
 #define ARCH_CTX_A2   rdx
@@ -45,3 +46,8 @@ struct arch_context {
 #define ARCH_CTX_A5   r9
 #define ARCH_CTX_RET0 rax
 #define ARCH_CTX_RET1 rdx
+
+struct arch_syscall_restart {
+    uint64_t rax;
+    uint64_t rdx;
+};