selftests/hid: Add test for hid_bpf_hw_output_report

This time we need to ensure uhid receives it, thus the new mutex and
condition.

Link: https://lore.kernel.org/r/20240315-b4-hid-bpf-new-funcs-v4-4-079c282469d3@kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

tools/testing/selftests/hid/hid_bpf.c

@@ -16,6 +16,11 @@
 
 #define SHOW_UHID_DEBUG 0
 
+#define min(a, b) \
+	({ __typeof__(a) _a = (a); \
+	__typeof__(b) _b = (b); \
+	_a < _b ? _a : _b; })
+
 static unsigned char rdesc[] = {
 	0x06, 0x00, 0xff,	/* Usage Page (Vendor Defined Page 1) */
 	0x09, 0x21,		/* Usage (Vendor Usage 0x21) */
@@ -111,6 +116,10 @@ struct hid_hw_request_syscall_args {
 static pthread_mutex_t uhid_started_mtx = PTHREAD_MUTEX_INITIALIZER;
 static pthread_cond_t uhid_started = PTHREAD_COND_INITIALIZER;
 
+static pthread_mutex_t uhid_output_mtx = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t uhid_output_cond = PTHREAD_COND_INITIALIZER;
+static unsigned char output_report[10];
+
 /* no need to protect uhid_stopped, only one thread accesses it */
 static bool uhid_stopped;
 
@@ -205,6 +214,13 @@ static int uhid_event(struct __test_metadata *_metadata, int fd)
 		break;
 	case UHID_OUTPUT:
 		UHID_LOG("UHID_OUTPUT from uhid-dev");
+
+		pthread_mutex_lock(&uhid_output_mtx);
+		memcpy(output_report,
+		       ev.u.output.data,
+		       min(ev.u.output.size, sizeof(output_report)));
+		pthread_cond_signal(&uhid_output_cond);
+		pthread_mutex_unlock(&uhid_output_mtx);
 		break;
 	case UHID_GET_REPORT:
 		UHID_LOG("UHID_GET_REPORT from uhid-dev");
@@ -733,6 +749,53 @@ TEST_F(hid_bpf, test_hid_change_report)
 	ASSERT_EQ(buf[2], 0) TH_LOG("leftovers_from_previous_test");
 }
 
+/*
+ * Call hid_bpf_hw_output_report against the given uhid device,
+ * check that the program is called and does the expected.
+ */
+TEST_F(hid_bpf, test_hid_user_output_report_call)
+{
+	struct hid_hw_request_syscall_args args = {
+		.retval = -1,
+		.size = 10,
+	};
+	DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattrs,
+			    .ctx_in = &args,
+			    .ctx_size_in = sizeof(args),
+	);
+	int err, cond_err, prog_fd;
+	struct timespec time_to_wait;
+
+	LOAD_BPF;
+
+	args.hid = self->hid_id;
+	args.data[0] = 1; /* report ID */
+	args.data[1] = 2; /* report ID */
+	args.data[2] = 42; /* report ID */
+
+	prog_fd = bpf_program__fd(self->skel->progs.hid_user_output_report);
+
+	pthread_mutex_lock(&uhid_output_mtx);
+
+	memset(output_report, 0, sizeof(output_report));
+	clock_gettime(CLOCK_REALTIME, &time_to_wait);
+	time_to_wait.tv_sec += 2;
+
+	err = bpf_prog_test_run_opts(prog_fd, &tattrs);
+	cond_err = pthread_cond_timedwait(&uhid_output_cond, &uhid_output_mtx, &time_to_wait);
+
+	ASSERT_OK(err) TH_LOG("error while calling bpf_prog_test_run_opts");
+	ASSERT_OK(cond_err) TH_LOG("error while calling waiting for the condition");
+
+	ASSERT_EQ(args.retval, 3);
+
+	ASSERT_EQ(output_report[0], 1);
+	ASSERT_EQ(output_report[1], 2);
+	ASSERT_EQ(output_report[2], 42);
+
+	pthread_mutex_unlock(&uhid_output_mtx);
+}
+
 /*
  * Attach hid_user_raw_request to the given uhid device,
  * call the bpf program from userspace

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

@@ -101,6 +101,30 @@ int hid_user_raw_request(struct hid_hw_request_syscall_args *args)
 	return 0;
 }
 
+SEC("syscall")
+int hid_user_output_report(struct hid_hw_request_syscall_args *args)
+{
+	struct hid_bpf_ctx *ctx;
+	const size_t size = args->size;
+	int i, ret = 0;
+
+	if (size > sizeof(args->data))
+		return -7; /* -E2BIG */
+
+	ctx = hid_bpf_allocate_context(args->hid);
+	if (!ctx)
+		return -1; /* EPERM check */
+
+	ret = hid_bpf_hw_output_report(ctx,
+				       args->data,
+				       size);
+	args->retval = ret;
+
+	hid_bpf_release_context(ctx);
+
+	return 0;
+}
+
 static const __u8 rdesc[] = {
 	0x05, 0x01,				/* USAGE_PAGE (Generic Desktop) */
 	0x09, 0x32,				/* USAGE (Z) */

tools/testing/selftests/hid/progs/hid_bpf_helpers.h

@@ -94,5 +94,7 @@ extern int hid_bpf_hw_request(struct hid_bpf_ctx *ctx,
 			      size_t buf__sz,
 			      enum hid_report_type type,
 			      enum hid_class_request reqtype) __ksym;
+extern int hid_bpf_hw_output_report(struct hid_bpf_ctx *ctx,
+				    __u8 *buf, size_t buf__sz) __ksym;
 
 #endif /* __HID_BPF_HELPERS_H */