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authorAndrii Nakryiko <andriin@fb.com>2019-12-13 17:43:29 -0800
committerAlexei Starovoitov <ast@kernel.org>2019-12-15 15:58:05 -0800
commit544402d4b49332a4a9b2b8fff20f9d9f5ef86559 (patch)
treeaea0437dbae1de2c6db8bc2bf4fd50ad6bc7a191 /tools/lib/bpf/libbpf_common.h
parentlibbpf: Add BPF_EMBED_OBJ macro for embedding BPF .o files (diff)
downloadlinux-dev-544402d4b49332a4a9b2b8fff20f9d9f5ef86559.tar.xz
linux-dev-544402d4b49332a4a9b2b8fff20f9d9f5ef86559.zip
libbpf: Extract common user-facing helpers
LIBBPF_API and DECLARE_LIBBPF_OPTS are needed in many public libbpf API headers. Extract them into libbpf_common.h to avoid unnecessary interdependency between btf.h, libbpf.h, and bpf.h or code duplication. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191214014341.3442258-6-andriin@fb.com
Diffstat (limited to '')
-rw-r--r--tools/lib/bpf/libbpf_common.h38
1 files changed, 38 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf_common.h b/tools/lib/bpf/libbpf_common.h
new file mode 100644
index 000000000000..4fb833840961
--- /dev/null
+++ b/tools/lib/bpf/libbpf_common.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Common user-facing libbpf helpers.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+
+#ifndef __LIBBPF_LIBBPF_COMMON_H
+#define __LIBBPF_LIBBPF_COMMON_H
+
+#ifndef LIBBPF_API
+#define LIBBPF_API __attribute__((visibility("default")))
+#endif
+
+/* Helper macro to declare and initialize libbpf options struct
+ *
+ * This dance with uninitialized declaration, followed by memset to zero,
+ * followed by assignment using compound literal syntax is done to preserve
+ * ability to use a nice struct field initialization syntax and **hopefully**
+ * have all the padding bytes initialized to zero. It's not guaranteed though,
+ * when copying literal, that compiler won't copy garbage in literal's padding
+ * bytes, but that's the best way I've found and it seems to work in practice.
+ *
+ * Macro declares opts struct of given type and name, zero-initializes,
+ * including any extra padding, it with memset() and then assigns initial
+ * values provided by users in struct initializer-syntax as varargs.
+ */
+#define DECLARE_LIBBPF_OPTS(TYPE, NAME, ...) \
+ struct TYPE NAME = ({ \
+ memset(&NAME, 0, sizeof(struct TYPE)); \
+ (struct TYPE) { \
+ .sz = sizeof(struct TYPE), \
+ __VA_ARGS__ \
+ }; \
+ })
+
+#endif /* __LIBBPF_LIBBPF_COMMON_H */