Commit 7715f549 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
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libbpf: Complete field-based CO-RE helpers with field offset helper 



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: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220509004148.1801791-6-andrii@kernel.org
parent 2a4ca46b

tools/lib/bpf/bpf_core_read.h

+12 −0
Original line number Diff line number Diff line
@@ -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