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From: Benjamin Tissoires <bentiss@kernel.org>
Date: Tue, 28 May 2024 15:14:47 +0200
Subject: [PATCH HID 09/13] selftests/hid: add subprog call test
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Message-Id: <20240528-hid_bpf_struct_ops-v1-9-8c6663df27d8@kernel.org>
References: <20240528-hid_bpf_struct_ops-v1-0-8c6663df27d8@kernel.org>
In-Reply-To: <20240528-hid_bpf_struct_ops-v1-0-8c6663df27d8@kernel.org>
To: Shuah Khan <shuah@kernel.org>, Jiri Kosina <jikos@kernel.org>, 
 Jonathan Corbet <corbet@lwn.net>, Alexei Starovoitov <ast@kernel.org>
Cc: linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, 
 bpf@vger.kernel.org, linux-input@vger.kernel.org, linux-doc@vger.kernel.org, 
 Benjamin Tissoires <bentiss@kernel.org>

I got a weird verifier error with a subprog once, so let's have a test
for it.

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
 tools/testing/selftests/hid/hid_bpf.c   | 41 +++++++++++++++++++++++++++++++++
 tools/testing/selftests/hid/progs/hid.c | 24 +++++++++++++++++++
 2 files changed, 65 insertions(+)

diff --git a/tools/testing/selftests/hid/hid_bpf.c b/tools/testing/selftests/hid/hid_bpf.c
index 967dfe6b58cb..45e173db35bd 100644
--- a/tools/testing/selftests/hid/hid_bpf.c
+++ b/tools/testing/selftests/hid/hid_bpf.c
@@ -638,6 +638,47 @@ TEST_F(hid_bpf, raw_event)
 	ASSERT_EQ(buf[2], 52);
 }
 
+/*
+ * Attach hid_first_event 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, subprog_raw_event)
+{
+	const struct test_program progs[] = {
+		{ .name = "hid_subprog_first_event" },
+	};
+	__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, 6) TH_LOG("read_hidraw");
+	ASSERT_EQ(buf[0], 1);
+	ASSERT_EQ(buf[2], 47);
+
+	/* inject another event */
+	memset(buf, 0, sizeof(buf));
+	buf[0] = 1;
+	buf[1] = 47;
+	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, 6) TH_LOG("read_hidraw");
+	ASSERT_EQ(buf[2], 52);
+}
+
 /*
  * Ensures that we can attach/detach programs
  */
diff --git a/tools/testing/selftests/hid/progs/hid.c b/tools/testing/selftests/hid/progs/hid.c
index 9adace26e8aa..efa3c7d292bc 100644
--- a/tools/testing/selftests/hid/progs/hid.c
+++ b/tools/testing/selftests/hid/progs/hid.c
@@ -35,6 +35,30 @@ struct hid_bpf_ops first_event = {
 	.hid_id = 2,
 };
 
+int __hid_subprog_first_event(struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
+{
+	__u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 3 /* size */);
+
+	if (!rw_data)
+		return 0; /* EPERM check */
+
+	rw_data[2] = rw_data[1] + 5;
+
+	return hid_ctx->size;
+}
+
+SEC("?struct_ops/hid_device_event")
+int BPF_PROG(hid_subprog_first_event, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
+{
+	return __hid_subprog_first_event(hid_ctx, type);
+}
+
+SEC(".struct_ops.link")
+struct hid_bpf_ops subprog_first_event = {
+	.hid_device_event = (void *)hid_subprog_first_event,
+	.hid_id = 2,
+};
+
 SEC("?struct_ops/hid_device_event")
 int BPF_PROG(hid_second_event, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
 {

-- 
2.44.0