Signal entry/exit works (crude)

include/sys/syscall.h

@@ -3,6 +3,13 @@
 #define SYSCALL_NR_READ         0
 #define SYSCALL_NR_WRITE        1
 
+#define SYSCALL_NRX_SIGENTRY    13
+void sys_sigentry(uintptr_t entry);
+#define SYSCALL_NR_SIGRETURN    15
+void sys_sigreturn(void);
+#define SYSCALL_NRX_SUICIDE     253
+void sys_suicide(void);
+
 #define SYSCALL_NR_FORK         57
 int sys_fork(void *ctx);
 #define SYSCALL_NR_EXIT         60

include/sys/thread.h

@@ -28,6 +28,9 @@ struct thread {
     uint64_t sleep_deadline;
     struct thread *wait_prev, *wait_next;
 
+    // Signal
+    uintptr_t signal_entry;
+
     // State
     pid_t pid;
     enum thread_state state;