[PATCHv8 bpf-next 07/29] bpf: Add bpf_trampoline_add/remove_prog functions
From: Jiri Olsa <jolsa@kernel.org>
Date: 2026-06-06 12:41:11
Also in:
bpf
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
Separate bpf_trampoline_add/remove_prog functions from __bpf_trampoline_link/unlink functions to be able to add/remove trampoline programs without the image being updated in following changes. No functional change is intended. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- kernel/bpf/trampoline.c | 108 +++++++++++++++++++++++----------------- 1 file changed, 61 insertions(+), 47 deletions(-)
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 1006031ea021..701138ef424a 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c@@ -820,41 +820,16 @@ static int bpf_freplace_check_tgt_prog(struct bpf_prog *tgt_prog) return 0; } -static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, - struct bpf_trampoline *tr, - struct bpf_prog *tgt_prog, - const struct bpf_trampoline_ops *ops, - void *data) +static int bpf_trampoline_add_prog(struct bpf_trampoline *tr, + struct bpf_tramp_link *link, + int cnt) { struct bpf_fsession_link *fslink = NULL; enum bpf_tramp_prog_type kind; struct bpf_tramp_link *link_exiting; struct hlist_head *prog_list; - int err = 0; - int cnt = 0, i; kind = bpf_attach_type_to_tramp(link->link.prog); - if (tr->extension_prog) - /* cannot attach fentry/fexit if extension prog is attached. - * cannot overwrite extension prog either. - */ - return -EBUSY; - - for (i = 0; i < BPF_TRAMP_MAX; i++) - cnt += tr->progs_cnt[i]; - - if (kind == BPF_TRAMP_REPLACE) { - /* Cannot attach extension if fentry/fexit are in use. */ - if (cnt) - return -EBUSY; - err = bpf_freplace_check_tgt_prog(tgt_prog); - if (err) - return err; - tr->extension_prog = link->link.prog; - return bpf_arch_text_poke(tr->func.addr, BPF_MOD_NOP, - BPF_MOD_JUMP, NULL, - link->link.prog->bpf_func); - } if (kind == BPF_TRAMP_FSESSION) { prog_list = &tr->progs_hlist[BPF_TRAMP_FENTRY]; cnt++;
@@ -882,17 +857,64 @@ static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, } else { tr->progs_cnt[kind]++; } - err = bpf_trampoline_update(tr, true /* lock_direct_mutex */, ops, data); - if (err) { - hlist_del_init(&link->tramp_hlist); - if (kind == BPF_TRAMP_FSESSION) { - tr->progs_cnt[BPF_TRAMP_FENTRY]--; - hlist_del_init(&fslink->fexit.tramp_hlist); - tr->progs_cnt[BPF_TRAMP_FEXIT]--; - } else { - tr->progs_cnt[kind]--; - } + return 0; +} + +static void bpf_trampoline_remove_prog(struct bpf_trampoline *tr, + struct bpf_tramp_link *link) +{ + struct bpf_fsession_link *fslink; + enum bpf_tramp_prog_type kind; + + kind = bpf_attach_type_to_tramp(link->link.prog); + if (kind == BPF_TRAMP_FSESSION) { + fslink = container_of(link, struct bpf_fsession_link, link.link); + hlist_del_init(&fslink->fexit.tramp_hlist); + tr->progs_cnt[BPF_TRAMP_FEXIT]--; + kind = BPF_TRAMP_FENTRY; + } + hlist_del_init(&link->tramp_hlist); + tr->progs_cnt[kind]--; +} + +static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, + struct bpf_trampoline *tr, + struct bpf_prog *tgt_prog, + const struct bpf_trampoline_ops *ops, + void *data) +{ + enum bpf_tramp_prog_type kind; + int err = 0; + int cnt = 0, i; + + kind = bpf_attach_type_to_tramp(link->link.prog); + if (tr->extension_prog) + /* cannot attach fentry/fexit if extension prog is attached. + * cannot overwrite extension prog either. + */ + return -EBUSY; + + for (i = 0; i < BPF_TRAMP_MAX; i++) + cnt += tr->progs_cnt[i]; + + if (kind == BPF_TRAMP_REPLACE) { + /* Cannot attach extension if fentry/fexit are in use. */ + if (cnt) + return -EBUSY; + err = bpf_freplace_check_tgt_prog(tgt_prog); + if (err) + return err; + tr->extension_prog = link->link.prog; + return bpf_arch_text_poke(tr->func.addr, BPF_MOD_NOP, + BPF_MOD_JUMP, NULL, + link->link.prog->bpf_func); } + err = bpf_trampoline_add_prog(tr, link, cnt); + if (err) + return err; + err = bpf_trampoline_update(tr, true /* lock_direct_mutex */, ops, data); + if (err) + bpf_trampoline_remove_prog(tr, link); return err; }
@@ -927,16 +949,8 @@ static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, guard(mutex)(&tgt_prog->aux->ext_mutex); tgt_prog->aux->is_extended = false; return err; - } else if (kind == BPF_TRAMP_FSESSION) { - struct bpf_fsession_link *fslink = - container_of(link, struct bpf_fsession_link, link.link); - - hlist_del_init(&fslink->fexit.tramp_hlist); - tr->progs_cnt[BPF_TRAMP_FEXIT]--; - kind = BPF_TRAMP_FENTRY; } - hlist_del_init(&link->tramp_hlist); - tr->progs_cnt[kind]--; + bpf_trampoline_remove_prog(tr, link); return bpf_trampoline_update(tr, true /* lock_direct_mutex */, ops, data); }
--
2.54.0