selftests/bpf: Test BPF_KPROBE_SYSCALL macro

Add tests for the newly added BPF_KPROBE_SYSCALL macro.
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220207143134.2977852-3-hengqi.chen@gmail.com

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

@@ -62,6 +62,12 @@ void test_bpf_syscall_macro(void)
 	ASSERT_EQ(skel->bss->arg4_core, exp_arg4, "syscall_arg4_core_variant");
 	ASSERT_EQ(skel->bss->arg5_core, exp_arg5, "syscall_arg5_core_variant");
 
+	ASSERT_EQ(skel->bss->option_syscall, exp_arg1, "BPF_KPROBE_SYSCALL_option");
+	ASSERT_EQ(skel->bss->arg2_syscall, exp_arg2, "BPF_KPROBE_SYSCALL_arg2");
+	ASSERT_EQ(skel->bss->arg3_syscall, exp_arg3, "BPF_KPROBE_SYSCALL_arg3");
+	ASSERT_EQ(skel->bss->arg4_syscall, exp_arg4, "BPF_KPROBE_SYSCALL_arg4");
+	ASSERT_EQ(skel->bss->arg5_syscall, exp_arg5, "BPF_KPROBE_SYSCALL_arg5");
+
 cleanup:
 	bpf_syscall_macro__destroy(skel);
 }

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

@@ -21,6 +21,12 @@ unsigned long arg4_core_cx = 0;
 unsigned long arg4_core = 0;
 unsigned long arg5_core = 0;
 
+int option_syscall = 0;
+unsigned long arg2_syscall = 0;
+unsigned long arg3_syscall = 0;
+unsigned long arg4_syscall = 0;
+unsigned long arg5_syscall = 0;
+
 const volatile pid_t filter_pid = 0;
 
 SEC("kprobe/" SYS_PREFIX "sys_prctl")
@@ -58,4 +64,21 @@ int BPF_KPROBE(handle_sys_prctl)
 	return 0;
 }
 
+SEC("kprobe/" SYS_PREFIX "sys_prctl")
+int BPF_KPROBE_SYSCALL(prctl_enter, int option, unsigned long arg2,
+		       unsigned long arg3, unsigned long arg4, unsigned long arg5)
+{
+	pid_t pid = bpf_get_current_pid_tgid() >> 32;
+
+	if (pid != filter_pid)
+		return 0;
+
+	option_syscall = option;
+	arg2_syscall = arg2;
+	arg3_syscall = arg3;
+	arg4_syscall = arg4;
+	arg5_syscall = arg5;
+	return 0;
+}
+
 char _license[] SEC("license") = "GPL";