Add bpf_core_field_offset() helper to complete field-based CO-RE
helpers. This helper can be useful for feature-detection and for some
more advanced cases of field reading (e.g., reading flexible array members).
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
tools/lib/bpf/bpf_core_read.h | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h
index 5ad415f9051f..fd48b1ff59ca 100644
--- a/tools/lib/bpf/bpf_core_read.h
+++ b/tools/lib/bpf/bpf_core_read.h
@@ -143,6 +143,18 @@ enum bpf_enum_value_kind {
#define bpf_core_field_size(field...) \
__builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_BYTE_SIZE)
+/*
+ * Convenience macro to get field's byte offset.
+ *
+ * Supports two forms:
+ * - field reference through variable access:
+ * bpf_core_field_offset(p->my_field);
+ * - field reference through type and field names:
+ * bpf_core_field_offset(struct my_type, my_field).
+ */
+#define bpf_core_field_offset(field...) \
+ __builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_BYTE_OFFSET)
+
/*
* Convenience macro to get BTF type ID of a specified type, using a local BTF
* information. Return 32-bit unsigned integer with type ID from program's own
--
2.30.2
