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

Quentin Monnet
2021-07-29T16:20:58Z

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@isovalent.com>
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