fix syscall script calls from outside so3 folder

Author: clemdiep

so3/Kbuild

@@ -6,8 +6,8 @@
 
 syscall-files = include/generated/syscall_table.h.in
 syscall-files += include/generated/syscall_number.h
-syscall-script = scripts/syscall_gen.sh
-syscall-src = syscall.tbl arch/$(SRCARCH)/syscall.h.in
+syscall-script = $(srctree)/scripts/syscall_gen.sh
+syscall-src = $(srctree)/syscall.tbl $(srctree)/arch/$(SRCARCH)/syscall.h.in
 
 quiet_cmd_syscall_gen = GEN     $@
       cmd_syscall_gen = $(syscall-script) $(syscall-src) $(syscall-files)

so3/arch/arm64/exception.S

@@ -564,13 +564,15 @@ el01_sync_handler:
 	mov	x0, sp
    	bl 	trap_handle
 
+#ifdef CONFIG_IPC_SIGNAL
 	// Check if sigreturn has been called. In this case, we
 	// clean the stack frame which has been used to manage the user handler.
 	cmp	x8, #SYSCALL_rt_sigreturn
 	bne	ret_from_fork
 
 	// Reset the stack frame by removing the one issued from sigreturn
 	add	sp, sp, #S_FRAME_SIZE
+#endif
 
 	// Entry point for new user threads
 ret_from_fork:

so3/kernel/main.c

@@ -78,7 +78,7 @@ void *rest_init(void *dummy)
 
 	kernel_thread(app_thread_main, "main_kernel", NULL, 0);
 
-	thread_exit(NULL);
+	thread_exit(0);
 
 #elif defined(CONFIG_PROC_ENV)