tests: userspace: cover missing/bad syscalls

We were missing code coverage for bad or unimplemented
system call IDs.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

kernel/userspace.c

@@ -762,15 +762,15 @@ static u32_t handler_bad_syscall(u32_t bad_id, u32_t arg2, u32_t arg3,
 {
 	printk("Bad system call id %u invoked\n", bad_id);
 	z_arch_syscall_oops(ssf);
-	CODE_UNREACHABLE;
+	CODE_UNREACHABLE; /* LCOV_EXCL_LINE */
 }
 
 static u32_t handler_no_syscall(u32_t arg1, u32_t arg2, u32_t arg3,
 				 u32_t arg4, u32_t arg5, u32_t arg6, void *ssf)
 {
 	printk("Unimplemented system call\n");
 	z_arch_syscall_oops(ssf);
-	CODE_UNREACHABLE;
+	CODE_UNREACHABLE; /* LCOV_EXCL_LINE */
 }
 
 #include <syscall_dispatch.c>

tests/kernel/mem_protect/userspace/src/main.c

@@ -1085,6 +1085,29 @@ void test_stack_buffer(void)
 
 }
 
+void z_impl_missing_syscall(void)
+{
+	/* Shouldn't ever get here; no handler function compiled */
+	k_panic();
+}
+
+void test_unimplemented_syscall(void)
+{
+	expect_fault = true;
+	expected_reason = REASON_KERNEL_OOPS;
+
+	missing_syscall();
+}
+
+void test_bad_syscall(void)
+{
+	expect_fault = true;
+	expected_reason = REASON_KERNEL_OOPS;
+
+	z_arch_syscall_invoke0(INT_MAX);
+
+}
+
 void test_main(void)
 {
 	struct k_mem_partition *parts[] = {&part0, &part1,
@@ -1134,7 +1157,9 @@ void test_main(void)
 			 ztest_unit_test(domain_add_part_context_switch),
 			 ztest_unit_test(domain_remove_part_context_switch),
 			 ztest_unit_test(domain_remove_thread_context_switch),
-			 ztest_unit_test(test_stack_buffer)
+			 ztest_unit_test(test_stack_buffer),
+			 ztest_user_unit_test(test_unimplemented_syscall),
+			 ztest_user_unit_test(test_bad_syscall)
 			 );
 	ztest_run_test_suite(userspace);
 }

tests/kernel/mem_protect/userspace/src/test_syscall.h

@@ -9,6 +9,7 @@
 
 __syscall void stack_info_get(u32_t *start_addr, u32_t *size);
 __syscall int check_perms(void *addr, size_t size, int write);
+__syscall void missing_syscall(void);
 
 #include <syscalls/test_syscall.h>