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bpf: Add bpf_trampoline_add/remove_prog functions

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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>
Link: https://lore.kernel.org/r/20260606123955.345967-8-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jiri Olsa
2026-06-06 14:39:32 +02:00
committed by Alexei Starovoitov
parent bf4bc3e11c
commit e6cc9ed677
1 changed files with 61 additions and 47 deletions
Download Patch File Download Diff File Expand all files Collapse all files

108
kernel/bpf/trampoline.c
View File

@@ -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);
}