selftests/hid: add test to change the report size

Use a different report with a bigger size and ensures we are doing
things properly.
Signed-off-by: NBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

tools/testing/selftests/hid/hid_bpf.c

@@ -22,6 +22,17 @@ static unsigned char rdesc[] = {
 	0xa1, 0x01,		/* COLLECTION (Application) */
 	0x09, 0x01,			/* Usage (Vendor Usage 0x01) */
 	0xa1, 0x00,			/* COLLECTION (Physical) */
+	0x85, 0x02,				/* REPORT_ID (2) */
+	0x19, 0x01,				/* USAGE_MINIMUM (1) */
+	0x29, 0x08,				/* USAGE_MAXIMUM (3) */
+	0x15, 0x00,				/* LOGICAL_MINIMUM (0) */
+	0x25, 0xff,				/* LOGICAL_MAXIMUM (255) */
+	0x95, 0x08,				/* REPORT_COUNT (8) */
+	0x75, 0x08,				/* REPORT_SIZE (8) */
+	0x81, 0x02,				/* INPUT (Data,Var,Abs) */
+	0xc0,				/* END_COLLECTION */
+	0x09, 0x01,			/* Usage (Vendor Usage 0x01) */
+	0xa1, 0x00,			/* COLLECTION (Physical) */
 	0x85, 0x01,				/* REPORT_ID (1) */
 	0x06, 0x00, 0xff,			/* Usage Page (Vendor Defined Page 1) */
 	0x19, 0x01,				/* USAGE_MINIMUM (1) */
@@ -645,6 +656,36 @@ TEST_F(hid_bpf, test_attach_detach)
 	ASSERT_EQ(buf[2], 47);
 }
 
+/*
+ * Attach hid_change_report_id to the given uhid device,
+ * retrieve and open the matching hidraw node,
+ * inject one event in the uhid device,
+ * check that the program sees it and can change the data
+ */
+TEST_F(hid_bpf, test_hid_change_report)
+{
+	const struct test_program progs[] = {
+		{ .name = "hid_change_report_id" },
+	};
+	__u8 buf[10] = {0};
+	int err;
+
+	LOAD_PROGRAMS(progs);
+
+	/* inject one event */
+	buf[0] = 1;
+	buf[1] = 42;
+	uhid_send_event(_metadata, self->uhid_fd, buf, 6);
+
+	/* read the data from hidraw */
+	memset(buf, 0, sizeof(buf));
+	err = read(self->hidraw_fd, buf, sizeof(buf));
+	ASSERT_EQ(err, 9) TH_LOG("read_hidraw");
+	ASSERT_EQ(buf[0], 2);
+	ASSERT_EQ(buf[1], 42);
+	ASSERT_EQ(buf[2], 0) TH_LOG("leftovers_from_previous_test");
+}
+
 static int libbpf_print_fn(enum libbpf_print_level level,
 			   const char *format, va_list args)
 {

tools/testing/selftests/hid/progs/hid.c

@@ -28,7 +28,20 @@ int BPF_PROG(hid_first_event, struct hid_bpf_ctx *hid_ctx)
 
 	rw_data[2] = rw_data[1] + 5;
 
-	return 0;
+	return hid_ctx->size;
+}
+
+SEC("?fmod_ret/hid_bpf_device_event")
+int BPF_PROG(hid_change_report_id, struct hid_bpf_ctx *hid_ctx)
+{
+	__u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 3 /* size */);
+
+	if (!rw_data)
+		return 0; /* EPERM check */
+
+	rw_data[0] = 2;
+
+	return 9;
 }
 
 SEC("syscall")