By default, the kernel btf that we load during loading program will be
freed after the programs are loaded in bpf_object_load(). However, we
still need to use these btf for tracing of multi-link during attaching.
Therefore, we don't free the btfs until the bpf object is closed if any
bpf programs of the type multi-link tracing exist.
Meanwhile, introduce the new api bpf_object__free_btf() to manually free
the btfs after attaching.
Signed-off-by: Menglong Dong <dongml2@xxxxxxxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 16 +++++++++++++++-
tools/lib/bpf/libbpf.h | 2 ++
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e9c641a2fb20..cfe81e1640d8 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8581,6 +8581,20 @@ static void bpf_object_post_load_cleanup(struct bpf_object *obj)
obj->btf_vmlinux = NULL;
}
+static void bpf_object_early_free_btf(struct bpf_object *obj)
+{
+ struct bpf_program *prog;
+
+ bpf_object__for_each_program(prog, obj) {
+ if (prog->expected_attach_type == BPF_TRACE_FENTRY_MULTI ||
+ prog->expected_attach_type == BPF_TRACE_FEXIT_MULTI ||
+ prog->expected_attach_type == BPF_MODIFY_RETURN_MULTI)
+ return;
+ }
+
+ bpf_object_post_load_cleanup(obj);
+}
+
static int bpf_object_prepare(struct bpf_object *obj, const char *target_btf_path)
{
int err;
@@ -8652,7 +8666,7 @@ static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const ch
err = bpf_gen__finish(obj->gen_loader, obj->nr_programs, obj->nr_maps);
}
- bpf_object_post_load_cleanup(obj);
+ bpf_object_early_free_btf(obj);
obj->state = OBJ_LOADED; /* doesn't matter if successfully or not */
if (err) {
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index d39f19c8396d..ded98e8cf327 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -323,6 +323,8 @@ LIBBPF_API struct bpf_program *
bpf_object__find_program_by_name(const struct bpf_object *obj,
const char *name);
+LIBBPF_API void bpf_object__free_btfs(struct bpf_object *obj);
+
LIBBPF_API int
libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
enum bpf_attach_type *expected_attach_type);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 1205f9a4fe04..23df00ae0b73 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -415,6 +415,7 @@ LIBBPF_1.4.0 {
bpf_token_create;
btf__new_split;
btf_ext__raw_data;
+ bpf_object__free_btfs;
} LIBBPF_1.3.0;
LIBBPF_1.5.0 {
--
2.39.5
