From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>
Subject: [PATCH bpf-next 5/9] libbpf: complete field-based CO-RE helpers with field offset helper
Date: Sun, 8 May 2022 17:41:44 -0700 [thread overview]
Message-ID: <20220509004148.1801791-6-andrii@kernel.org> (raw)
In-Reply-To: <20220509004148.1801791-1-andrii@kernel.org>
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@kernel.org>
---
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
next prev parent reply other threads:[~2022-05-09 1:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-09 0:41 [PATCH bpf-next 0/9] Misc libbpf fixes and small improvements Andrii Nakryiko
2022-05-09 0:41 ` [PATCH bpf-next 1/9] selftests/bpf: prevent skeleton generation race Andrii Nakryiko
2022-05-09 0:41 ` [PATCH bpf-next 2/9] libbpf: make __kptr and __kptr_ref unconditionally use btf_type_tag() attr Andrii Nakryiko
2022-12-26 11:34 ` [PATCH bpf-next 2/9] libbpf: make __kptr and __kptr_ref Rong Tao
2022-12-28 19:03 ` Yonghong Song
2022-05-09 0:41 ` [PATCH bpf-next 3/9] libbpf: improve usability of field-based CO-RE helpers Andrii Nakryiko
2022-05-09 0:41 ` [PATCH bpf-next 4/9] selftests/bpf: use both syntaxes for " Andrii Nakryiko
2022-05-09 0:41 ` Andrii Nakryiko [this message]
2022-05-09 0:41 ` [PATCH bpf-next 6/9] selftests/bpf: add bpf_core_field_offset() tests Andrii Nakryiko
2022-05-09 0:41 ` [PATCH bpf-next 7/9] libbpf: provide barrier() and barrier_var() in bpf_helpers.h Andrii Nakryiko
2022-05-09 0:41 ` [PATCH bpf-next 8/9] libbpf: automatically fix up BPF_MAP_TYPE_RINGBUF size, if necessary Andrii Nakryiko
2022-05-10 15:34 ` Nathan Chancellor
2022-05-10 18:47 ` Andrii Nakryiko
2022-05-09 0:41 ` [PATCH bpf-next 9/9] selftests/bpf: test libbpf's ringbuf size fix up logic Andrii Nakryiko
2022-05-09 15:20 ` [PATCH bpf-next 0/9] Misc libbpf fixes and small improvements patchwork-bot+netdevbpf
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