[PATCH bpf-next v4 3/7] libbpf: Support declarative manual load via SEC("!...") prefix
From: Andrey Grodzovsky <hidden>
Date: 2026-09-21 22:39:58
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 SEC("!...") section-name prefix, letting a program declare
itself manually-loaded in its source instead of requiring an
imperative bpf_program__set_load_strategy() call, following the exact
convention already used for SEC("?...").
The prefix is recognized and stripped in bpf_object__init_prog(),
before find_sec_def() ever runs, directly setting load_strategy to
MANUAL and initializing autoattach/saved_autoattach - the same place
and same style '?' already uses, and before BTF or sec_def exist.
Assisted-by: Claude:claude-sonnet-5
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Andrey Grodzovsky <redacted>
---
tools/lib/bpf/libbpf.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 61195d16ee0f..789d2df7eaae 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c@@ -890,16 +890,25 @@ bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog, /* libbpf's convention for SEC("?abc...") is that it's just like * SEC("abc...") but the corresponding bpf_program starts out with * autoload set to false. + * + * Similarly, SEC("!abc...") marks the program for manual loading: + * it is skipped by the bulk auto-load pass and must be explicitly + * loaded later via bpf_program__load_manually(). */ if (sec_name[0] == '?') { prog->load_strategy = BPF_PROG_LOAD_STRATEGY_DISABLED; /* from now on forget there was ? in section name */ sec_name++; + } else if (sec_name[0] == '!') { + prog->load_strategy = BPF_PROG_LOAD_STRATEGY_MANUAL; + /* from now on forget there was ! in section name */ + sec_name++; } else { prog->load_strategy = BPF_PROG_LOAD_STRATEGY_AUTO; } - prog->autoattach = true; + prog->saved_autoattach = true; + prog->autoattach = prog->load_strategy != BPF_PROG_LOAD_STRATEGY_MANUAL; /* inherit object's log_level */ prog->log_level = obj->log_level;
@@ -15399,7 +15408,7 @@ int bpf_program__set_load_strategy(struct bpf_program *prog, enum bpf_prog_load_ * A gen_loader implementation is being called for autoloaded * programs and defines its own model for loading BPF programs. * To pass a BPF program to gen_loader, set the program's load strategy - * to LD_AUTOLOAD. + * to BPF_PROG_LOAD_STRATEGY_AUTO. */ if (obj->gen_loader) return libbpf_err(-EOPNOTSUPP);
--
2.34.1