diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index a004b4cce99e..770f47adf295 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -1210,6 +1210,10 @@ TEST_F(TRACE_poke, getpid_runs_normally)
 # define ARCH_REGS	struct pt_regs
 # define SYSCALL_NUM	gpr[0]
 # define SYSCALL_RET	gpr[3]
+#elif defined(__s390__)
+# define ARCH_REGS     s390_regs
+# define SYSCALL_NUM   gprs[2]
+# define SYSCALL_RET   gprs[2]
 #else
 # error "Do not know how to find your architecture's registers and syscalls"
 #endif
@@ -1243,7 +1247,8 @@ void change_syscall(struct __test_metadata *_metadata,
 	ret = ptrace(PTRACE_GETREGSET, tracee, NT_PRSTATUS, &iov);
 	EXPECT_EQ(0, ret);
 
-#if defined(__x86_64__) || defined(__i386__) || defined(__aarch64__) || defined(__powerpc__)
+#if defined(__x86_64__) || defined(__i386__) || defined(__aarch64__) || \
+    defined(__powerpc__) || defined(__s390__)
 	{
 		regs.SYSCALL_NUM = syscall;
 	}
@@ -1281,17 +1286,21 @@ void tracer_syscall(struct __test_metadata *_metadata, pid_t tracee,
 	ret = ptrace(PTRACE_GETEVENTMSG, tracee, NULL, &msg);
 	EXPECT_EQ(0, ret);
 
+	/* Validate and take action on expected syscalls. */
 	switch (msg) {
 	case 0x1002:
 		/* change getpid to getppid. */
+		EXPECT_EQ(__NR_getpid, get_syscall(_metadata, tracee));
 		change_syscall(_metadata, tracee, __NR_getppid);
 		break;
 	case 0x1003:
 		/* skip gettid. */
+		EXPECT_EQ(__NR_gettid, get_syscall(_metadata, tracee));
 		change_syscall(_metadata, tracee, -1);
 		break;
 	case 0x1004:
 		/* do nothing (allow getppid) */
+		EXPECT_EQ(__NR_getppid, get_syscall(_metadata, tracee));
 		break;
 	default:
 		EXPECT_EQ(0, msg) {
@@ -1409,6 +1418,8 @@ TEST_F(TRACE_syscall, syscall_dropped)
 #  define __NR_seccomp 277
 # elif defined(__powerpc__)
 #  define __NR_seccomp 358
+# elif defined(__s390__)
+#  define __NR_seccomp 348
 # else
 #  warning "seccomp syscall number unknown for this architecture"
 #  define __NR_seccomp 0xffff
@@ -1453,6 +1464,9 @@ TEST(seccomp_syscall)
 
 	/* Reject insane operation. */
 	ret = seccomp(-1, 0, &prog);
+	ASSERT_NE(ENOSYS, errno) {
+		TH_LOG("Kernel does not support seccomp syscall!");
+	}
 	EXPECT_EQ(EINVAL, errno) {
 		TH_LOG("Did not reject crazy op value!");
 	}
@@ -1501,6 +1515,9 @@ TEST(seccomp_syscall_mode_lock)
 	}
 
 	ret = seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog);
+	ASSERT_NE(ENOSYS, errno) {
+		TH_LOG("Kernel does not support seccomp syscall!");
+	}
 	EXPECT_EQ(0, ret) {
 		TH_LOG("Could not install filter!");
 	}
@@ -1535,6 +1552,9 @@ TEST(TSYNC_first)
 
 	ret = seccomp(SECCOMP_SET_MODE_FILTER, SECCOMP_FLAG_FILTER_TSYNC,
 		      &prog);
+	ASSERT_NE(ENOSYS, errno) {
+		TH_LOG("Kernel does not support seccomp syscall!");
+	}
 	EXPECT_EQ(0, ret) {
 		TH_LOG("Could not install initial filter with TSYNC!");
 	}
@@ -1694,6 +1714,9 @@ TEST_F(TSYNC, siblings_fail_prctl)
 
 	/* Check prctl failure detection by requesting sib 0 diverge. */
 	ret = seccomp(SECCOMP_SET_MODE_FILTER, 0, &prog);
+	ASSERT_NE(ENOSYS, errno) {
+		TH_LOG("Kernel does not support seccomp syscall!");
+	}
 	ASSERT_EQ(0, ret) {
 		TH_LOG("setting filter failed");
 	}
@@ -1731,6 +1754,9 @@ TEST_F(TSYNC, two_siblings_with_ancestor)
 	}
 
 	ret = seccomp(SECCOMP_SET_MODE_FILTER, 0, &self->root_prog);
+	ASSERT_NE(ENOSYS, errno) {
+		TH_LOG("Kernel does not support seccomp syscall!");
+	}
 	ASSERT_EQ(0, ret) {
 		TH_LOG("Kernel does not support SECCOMP_SET_MODE_FILTER!");
 	}
@@ -1805,6 +1831,9 @@ TEST_F(TSYNC, two_siblings_with_no_filter)
 
 	ret = seccomp(SECCOMP_SET_MODE_FILTER, SECCOMP_FLAG_FILTER_TSYNC,
 		      &self->apply_prog);
+	ASSERT_NE(ENOSYS, errno) {
+		TH_LOG("Kernel does not support seccomp syscall!");
+	}
 	ASSERT_EQ(0, ret) {
 		TH_LOG("Could install filter on all threads!");
 	}
@@ -1833,6 +1862,9 @@ TEST_F(TSYNC, two_siblings_with_one_divergence)
 	}
 
 	ret = seccomp(SECCOMP_SET_MODE_FILTER, 0, &self->root_prog);
+	ASSERT_NE(ENOSYS, errno) {
+		TH_LOG("Kernel does not support seccomp syscall!");
+	}
 	ASSERT_EQ(0, ret) {
 		TH_LOG("Kernel does not support SECCOMP_SET_MODE_FILTER!");
 	}
@@ -1890,6 +1922,9 @@ TEST_F(TSYNC, two_siblings_not_under_filter)
 	}
 
 	ret = seccomp(SECCOMP_SET_MODE_FILTER, 0, &self->root_prog);
+	ASSERT_NE(ENOSYS, errno) {
+		TH_LOG("Kernel does not support seccomp syscall!");
+	}
 	ASSERT_EQ(0, ret) {
 		TH_LOG("Kernel does not support SECCOMP_SET_MODE_FILTER!");
 	}
diff --git a/tools/testing/selftests/seccomp/test_harness.h b/tools/testing/selftests/seccomp/test_harness.h
index 977a6afc4489..fb2841601f2f 100644
--- a/tools/testing/selftests/seccomp/test_harness.h
+++ b/tools/testing/selftests/seccomp/test_harness.h
@@ -370,11 +370,8 @@
 	__typeof__(_expected) __exp = (_expected); \
 	__typeof__(_seen) __seen = (_seen); \
 	if (!(__exp _t __seen)) { \
-		unsigned long long __exp_print = 0; \
-		unsigned long long __seen_print = 0; \
-		/* Avoid casting complaints the scariest way we can. */ \
-		memcpy(&__exp_print, &__exp, sizeof(__exp)); \
-		memcpy(&__seen_print, &__seen, sizeof(__seen)); \
+		unsigned long long __exp_print = (unsigned long long)__exp; \
+		unsigned long long __seen_print = (unsigned long long)__seen; \
 		__TH_LOG("Expected %s (%llu) %s %s (%llu)", \
 			 #_expected, __exp_print, #_t, \
 			 #_seen, __seen_print); \