6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tao Chen <chen.dylane@xxxxxxxxx>
[ Upstream commit a400d08b3014a4f4e939366bb6fd769b9caff4c9 ]
Referenced commit broke the logic of resetting expected_attach_type to
zero for allowed program types if kernel doesn't yet support such field.
We do need to overwrite and preserve expected_attach_type for
multi-uprobe though, but that can be done explicitly in
libbpf_prepare_prog_load().
Fixes: 5902da6d8a52 ("libbpf: Add uprobe multi link support to bpf_program__attach_usdt")
Suggested-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20240925153012.212866-1-chen.dylane@xxxxxxxxx
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ceed16a10285a..834b3e6bc72c3 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -6837,8 +6837,14 @@ static int libbpf_prepare_prog_load(struct bpf_program *prog,
opts->prog_flags |= BPF_F_XDP_HAS_FRAGS;
/* special check for usdt to use uprobe_multi link */
- if ((def & SEC_USDT) && kernel_supports(prog->obj, FEAT_UPROBE_MULTI_LINK))
+ if ((def & SEC_USDT) && kernel_supports(prog->obj, FEAT_UPROBE_MULTI_LINK)) {
+ /* for BPF_TRACE_UPROBE_MULTI, user might want to query expected_attach_type
+ * in prog, and expected_attach_type we set in kernel is from opts, so we
+ * update both.
+ */
prog->expected_attach_type = BPF_TRACE_UPROBE_MULTI;
+ opts->expected_attach_type = BPF_TRACE_UPROBE_MULTI;
+ }
if ((def & SEC_ATTACH_BTF) && !prog->attach_btf_id) {
int btf_obj_fd = 0, btf_type_id = 0, err;
@@ -6915,6 +6921,7 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog
load_attr.attach_btf_id = prog->attach_btf_id;
load_attr.kern_version = kern_version;
load_attr.prog_ifindex = prog->prog_ifindex;
+ load_attr.expected_attach_type = prog->expected_attach_type;
/* specify func_info/line_info only if kernel supports them */
btf_fd = bpf_object__btf_fd(obj);
@@ -6943,9 +6950,6 @@ static int bpf_object_load_prog(struct bpf_object *obj, struct bpf_program *prog
insns_cnt = prog->insns_cnt;
}
- /* allow prog_prepare_load_fn to change expected_attach_type */
- load_attr.expected_attach_type = prog->expected_attach_type;
-
if (obj->gen_loader) {
bpf_gen__prog_load(obj->gen_loader, prog->type, prog->name,
license, insns, insns_cnt, &load_attr,
--
2.43.0
