netdev - [PATCH bpf-next v3 7/8] libbpf: add split BTF support for btf__load_from_kernel_by

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Message-Id: <20210729162028.29512-8-quentin@isovalent.com>
Date:   Thu, 29 Jul 2021 17:20:27 +0100
From:   Quentin Monnet <quentin@...valent.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        Quentin Monnet <quentin@...valent.com>,
        John Fastabend <john.fastabend@...il.com>
Subject: [PATCH bpf-next v3 7/8] libbpf: add split BTF support for btf__load_from_kernel_by_id()

Add a new API function btf__load_from_kernel_by_id_split(), which takes
a pointer to a base BTF object in order to support split BTF objects
when retrieving BTF information from the kernel.

Reference: https://github.com/libbpf/libbpf/issues/314

Signed-off-by: Quentin Monnet <quentin@...valent.com>
Acked-by: John Fastabend <john.fastabend@...il.com>
---
 tools/lib/bpf/btf.c      | 9 +++++++--
 tools/lib/bpf/btf.h      | 1 +
 tools/lib/bpf/libbpf.map | 1 +
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 948c29fee447..cafa4f6bd9b1 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -1383,7 +1383,7 @@ struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf)
 	return btf;
 }
 
-struct btf *btf__load_from_kernel_by_id(__u32 id)
+struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf)
 {
 	struct btf *btf;
 	int btf_fd;
@@ -1392,12 +1392,17 @@ struct btf *btf__load_from_kernel_by_id(__u32 id)
 	if (btf_fd < 0)
 		return libbpf_err_ptr(-errno);
 
-	btf = btf_get_from_fd(btf_fd, NULL);
+	btf = btf_get_from_fd(btf_fd, base_btf);
 	close(btf_fd);
 
 	return libbpf_ptr(btf);
 }
 
+struct btf *btf__load_from_kernel_by_id(__u32 id)
+{
+	return btf__load_from_kernel_by_id_split(id, NULL);
+}
+
 int btf__get_from_id(__u32 id, struct btf **btf)
 {
 	struct btf *res;
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index a6039ca66895..358046ffc7bd 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -44,6 +44,7 @@ LIBBPF_API struct btf *btf__parse_elf_split(const char *path, struct btf *base_b
 LIBBPF_API struct btf *btf__parse_raw(const char *path);
 LIBBPF_API struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf);
 LIBBPF_API struct btf *btf__load_from_kernel_by_id(__u32 id);
+LIBBPF_API struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf);
 LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__load_from_kernel_by_id instead")
 LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
 
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 3a9c6939301e..5aca3686ca5e 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -376,6 +376,7 @@ LIBBPF_0.5.0 {
 		bpf_program__attach_kprobe_opts;
 		bpf_object__gen_loader;
 		btf__load_from_kernel_by_id;
+		btf__load_from_kernel_by_id_split;
 		btf__load_into_kernel;
 		btf_dump__dump_type_data;
 		libbpf_set_strict_mode;
-- 
2.30.2