From: Ian Rogers <irogers@google.com>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Stanislav Fomichev <sdf@google.com>, Ian Rogers <irogers@google.com>
Subject: [PATCH] libbpf bpf_helpers: Use __builtin_offsetof for offsetof if available
Date: Fri, 17 Jul 2020 00:23:19 -0700 [thread overview]
Message-ID: <20200717072319.101302-1-irogers@google.com> (raw)
The non-builtin route for offsetof has a dependency on size_t from
stdlib.h/stdint.h that is undeclared and may break targets.
The offsetof macro in bpf_helpers may disable the same macro in other
headers that have a #ifdef offsetof guard. Rather than add additional
dependencies improve the offsetof macro declared here to use the
builtin if available.
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/lib/bpf/bpf_helpers.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index a510d8ed716f..ed2ac74fc515 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -40,8 +40,12 @@
* Helper macro to manipulate data structures
*/
#ifndef offsetof
+#if __has_builtin(__builtin_offsetof)
+#define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER)
+#else
#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER)
#endif
+#endif
#ifndef container_of
#define container_of(ptr, type, member) \
({ \
--
2.28.0.rc0.105.gf9edc3c819-goog
next reply other threads:[~2020-07-17 7:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-17 7:23 Ian Rogers [this message]
2020-07-18 6:00 ` [PATCH] libbpf bpf_helpers: Use __builtin_offsetof for offsetof if available Yonghong Song
2020-07-19 3:52 ` Andrii Nakryiko
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