selftests/bpf: Enable test_bpf_syscall_macro: Syscall_arg1 on s390 and arm64

Considering that CO-RE direct read access to the first system call
argument is already available on s390 and arm64, let's enable
test_bpf_syscall_macro:syscall_arg1 on these architectures.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240831041934.1629216-4-pulehui@huaweicloud.com

tools/testing/selftests/bpf/prog_tests/test_bpf_syscall_macro.c

@@ -38,11 +38,7 @@ void test_bpf_syscall_macro(void)
 	/* check whether args of syscall are copied correctly */
 	prctl(exp_arg1, exp_arg2, exp_arg3, exp_arg4, exp_arg5);
 
-#if defined(__aarch64__) || defined(__s390__)
-	ASSERT_NEQ(skel->bss->arg1, exp_arg1, "syscall_arg1");
-#else
 	ASSERT_EQ(skel->bss->arg1, exp_arg1, "syscall_arg1");
-#endif
 	ASSERT_EQ(skel->bss->arg2, exp_arg2, "syscall_arg2");
 	ASSERT_EQ(skel->bss->arg3, exp_arg3, "syscall_arg3");
 	/* it cannot copy arg4 when uses PT_REGS_PARM4 on x86_64 */

tools/testing/selftests/bpf/progs/bpf_syscall_macro.c

@@ -43,9 +43,7 @@ int BPF_KPROBE(handle_sys_prctl)
 
 	/* test for PT_REGS_PARM */
 
-#if !defined(bpf_target_arm64) && !defined(bpf_target_s390)
 	bpf_probe_read_kernel(&tmp, sizeof(tmp), &PT_REGS_PARM1_SYSCALL(real_regs));
-#endif
 	arg1 = tmp;
 	bpf_probe_read_kernel(&arg2, sizeof(arg2), &PT_REGS_PARM2_SYSCALL(real_regs));
 	bpf_probe_read_kernel(&arg3, sizeof(arg3), &PT_REGS_PARM3_SYSCALL(real_regs));