[PATCHv3 bpf-next 03/24] bpf: Add struct bpf_trampoline_ops object
From: Jiri Olsa <jolsa@kernel.org>
Date: 2026-03-16 07:52:23
Also in:
linux-trace-kernel
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
In following changes we will need to override ftrace direct attachment behaviour. In order to do that we are adding struct bpf_trampoline_ops object that defines callbacks for ftrace direct attachment: register_fentry unregister_fentry modify_fentry The new struct bpf_trampoline_ops object is passed as an argument to __bpf_trampoline_link/unlink_prog functions. At the moment the default trampoline_ops is set to the current ftrace direct attachment functions, so there's no functional change for the current code. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- kernel/bpf/trampoline.c | 59 ++++++++++++++++++++++++++++------------- 1 file changed, 41 insertions(+), 18 deletions(-)
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 9923703a1544..d72057c715bd 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c@@ -58,8 +58,18 @@ static void trampoline_unlock(struct bpf_trampoline *tr) mutex_unlock(select_trampoline_lock(tr)); } +struct bpf_trampoline_ops { + int (*register_fentry)(struct bpf_trampoline *tr, void *new_addr, void *data); + int (*unregister_fentry)(struct bpf_trampoline *tr, u32 orig_flags, void *old_addr, + void *data); + int (*modify_fentry)(struct bpf_trampoline *tr, u32 orig_flags, void *old_addr, + void *new_addr, bool lock_direct_mutex, void *data); +}; + #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS -static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex); +static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex, + struct bpf_trampoline_ops *ops, void *data); +static struct bpf_trampoline_ops trampoline_ops; #ifdef CONFIG_HAVE_SINGLE_FTRACE_DIRECT_OPS static struct bpf_trampoline *direct_ops_ip_lookup(struct ftrace_ops *ops, unsigned long ip)
@@ -144,13 +154,15 @@ static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, unsigned long ip, if ((tr->flags & BPF_TRAMP_F_CALL_ORIG) && !(tr->flags & BPF_TRAMP_F_ORIG_STACK)) - ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */); + ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */, + &trampoline_ops, NULL); break; case FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER: tr->flags &= ~BPF_TRAMP_F_SHARE_IPMODIFY; if (tr->flags & BPF_TRAMP_F_ORIG_STACK) - ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */); + ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */, + &trampoline_ops, NULL); break; default: ret = -EINVAL;
@@ -414,7 +426,7 @@ static int bpf_trampoline_update_fentry(struct bpf_trampoline *tr, u32 orig_flag } static int unregister_fentry(struct bpf_trampoline *tr, u32 orig_flags, - void *old_addr) + void *old_addr, void *data) { int ret;
@@ -428,7 +440,7 @@ static int unregister_fentry(struct bpf_trampoline *tr, u32 orig_flags, static int modify_fentry(struct bpf_trampoline *tr, u32 orig_flags, void *old_addr, void *new_addr, - bool lock_direct_mutex) + bool lock_direct_mutex, void *data __maybe_unused) { int ret;
@@ -442,7 +454,7 @@ static int modify_fentry(struct bpf_trampoline *tr, u32 orig_flags, } /* first time registering */ -static int register_fentry(struct bpf_trampoline *tr, void *new_addr) +static int register_fentry(struct bpf_trampoline *tr, void *new_addr, void *data __maybe_unused) { void *ip = tr->func.addr; unsigned long faddr;
@@ -464,6 +476,12 @@ static int register_fentry(struct bpf_trampoline *tr, void *new_addr) return ret; } +static struct bpf_trampoline_ops trampoline_ops = { + .register_fentry = register_fentry, + .unregister_fentry = unregister_fentry, + .modify_fentry = modify_fentry, +}; + static struct bpf_tramp_links * bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg) {
@@ -631,7 +649,8 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, int size) return ERR_PTR(err); } -static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex) +static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex, + struct bpf_trampoline_ops *ops, void *data) { struct bpf_tramp_image *im; struct bpf_tramp_links *tlinks;
@@ -644,7 +663,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut return PTR_ERR(tlinks); if (total == 0) { - err = unregister_fentry(tr, orig_flags, tr->cur_image->image); + err = ops->unregister_fentry(tr, orig_flags, tr->cur_image->image, data); bpf_tramp_image_put(tr->cur_image); tr->cur_image = NULL; goto out;
@@ -715,11 +734,11 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut WARN_ON(tr->cur_image && total == 0); if (tr->cur_image) /* progs already running at this address */ - err = modify_fentry(tr, orig_flags, tr->cur_image->image, - im->image, lock_direct_mutex); + err = ops->modify_fentry(tr, orig_flags, tr->cur_image->image, + im->image, lock_direct_mutex, data); else /* first time registering */ - err = register_fentry(tr, im->image); + err = ops->register_fentry(tr, im->image, data); #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS if (err == -EAGAIN) {
@@ -793,7 +812,9 @@ static int bpf_freplace_check_tgt_prog(struct bpf_prog *tgt_prog) static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr, - struct bpf_prog *tgt_prog) + struct bpf_prog *tgt_prog, + struct bpf_trampoline_ops *ops, + void *data) { struct bpf_fsession_link *fslink = NULL; enum bpf_tramp_prog_type kind;
@@ -851,7 +872,7 @@ 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 */); + err = bpf_trampoline_update(tr, true /* lock_direct_mutex */, ops, data); if (err) { hlist_del_init(&link->tramp_hlist); if (kind == BPF_TRAMP_FSESSION) {
@@ -872,14 +893,16 @@ int bpf_trampoline_link_prog(struct bpf_tramp_link *link, int err; trampoline_lock(tr); - err = __bpf_trampoline_link_prog(link, tr, tgt_prog); + err = __bpf_trampoline_link_prog(link, tr, tgt_prog, &trampoline_ops, NULL); trampoline_unlock(tr); return err; } static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr, - struct bpf_prog *tgt_prog) + struct bpf_prog *tgt_prog, + struct bpf_trampoline_ops *ops, + void *data) { enum bpf_tramp_prog_type kind; int err;
@@ -904,7 +927,7 @@ static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, } hlist_del_init(&link->tramp_hlist); tr->progs_cnt[kind]--; - return bpf_trampoline_update(tr, true /* lock_direct_mutex */); + return bpf_trampoline_update(tr, true /* lock_direct_mutex */, ops, data); } /* bpf_trampoline_unlink_prog() should never fail. */
@@ -915,7 +938,7 @@ int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, int err; trampoline_lock(tr); - err = __bpf_trampoline_unlink_prog(link, tr, tgt_prog); + err = __bpf_trampoline_unlink_prog(link, tr, tgt_prog, &trampoline_ops, NULL); trampoline_unlock(tr); return err; }
@@ -1044,7 +1067,7 @@ int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog, goto err; } - err = __bpf_trampoline_link_prog(&shim_link->link, tr, NULL); + err = __bpf_trampoline_link_prog(&shim_link->link, tr, NULL, &trampoline_ops, NULL); if (err) goto err;
--
2.53.0