Thread (14 messages) 14 messages, 2 authors, 2021-07-30
STALE1764d LANDED: 5 (5M)

[PATCH bpf-next v3 7/8] libbpf: add split BTF support for btf__load_from_kernel_by_id()

From: Quentin Monnet <hidden>
Date: 2021-07-29 16:20:58
Also in: netdev
Subsystem: bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds

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 <redacted>
Acked-by: John Fastabend <john.fastabend@gmail.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
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