selftests/hid: fix compilation when bpf_wq and hid_device are not exported

This can happen in situations when CONFIG_HID_SUPPORT is set to no, or
some complex situations where struct bpf_wq is not exported.

So do the usual dance of hiding them before including vmlinux.h, and
then redefining them and make use of CO-RE to have the correct offsets.

Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Fixes: fe8d561 ("selftests/hid: add wq test for hid_bpf_input_report()")
Cc: [email protected]
Acked-by: Jiri Kosina <[email protected]>
Reviewed-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Benjamin Tissoires <[email protected]>

Author: Benjamin Tissoires

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

@@ -6,8 +6,10 @@
 #define __HID_BPF_HELPERS_H
 
 /* "undefine" structs and enums in vmlinux.h, because we "override" them below */
+#define bpf_wq bpf_wq___not_used
 #define hid_bpf_ctx hid_bpf_ctx___not_used
 #define hid_bpf_ops hid_bpf_ops___not_used
+#define hid_device hid_device___not_used
 #define hid_report_type hid_report_type___not_used
 #define hid_class_request hid_class_request___not_used
 #define hid_bpf_attach_flags hid_bpf_attach_flags___not_used
@@ -27,8 +29,10 @@
 
 #include "vmlinux.h"
 
+#undef bpf_wq
 #undef hid_bpf_ctx
 #undef hid_bpf_ops
+#undef hid_device
 #undef hid_report_type
 #undef hid_class_request
 #undef hid_bpf_attach_flags
@@ -55,6 +59,14 @@ enum hid_report_type {
 	HID_REPORT_TYPES,
 };
 
+struct hid_device {
+	unsigned int id;
+} __attribute__((preserve_access_index));
+
+struct bpf_wq {
+	__u64 __opaque[2];
+};
+
 struct hid_bpf_ctx {
 	struct hid_device *hid;
 	__u32 allocated_size;