From: Kaitao Cheng <kaitao.cheng@linux.dev>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
Shuah Khan <shuah@kernel.org>, Leon Hwang <leon.hwang@linux.dev>
Cc: bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-kernel@vger.kernel.org,
Kaitao Cheng <chengkaitao@kylinos.cn>
Subject: [PATCH bpf-next v2 2/3] bpf: Mark existing lock-safe kfuncs with KF_SPINLOCK_SAFE
Date: Wed, 5 Aug 2026 23:33:39 +0800 [thread overview]
Message-ID: <20260805153340.34776-3-kaitao.cheng@linux.dev> (raw)
In-Reply-To: <20260805153340.34776-1-kaitao.cheng@linux.dev>
From: Kaitao Cheng <chengkaitao@kylinos.cn>
The verifier currently keeps a hard-coded list of kfuncs that may be
called while holding a bpf_spin_lock. With KF_SPINLOCK_SAFE available,
retaining this list creates two sources of truth and requires verifier
changes whenever another lock-safe kfunc is added.
Mark every kfunc currently accepted by kfunc_spin_allowed() with
KF_SPINLOCK_SAFE. This covers the graph, numeric iterator, resource
spin lock, arena, and stream kfuncs.
Remove the obsolete category checks and make kfunc_spin_allowed() rely
solely on the kfunc registration metadata. This preserves the behavior
of existing kfuncs while using the same mechanism for built-in and
module kfuncs.
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
---
kernel/bpf/arena.c | 6 ++---
kernel/bpf/helpers.c | 56 +++++++++++++++++++++--------------------
kernel/bpf/rqspinlock.c | 8 +++---
kernel/bpf/verifier.c | 32 -----------------------
4 files changed, 36 insertions(+), 66 deletions(-)
diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c
index 555ee2531ef9..7b6847200b43 100644
--- a/kernel/bpf/arena.c
+++ b/kernel/bpf/arena.c
@@ -1118,9 +1118,9 @@ __bpf_kfunc int bpf_arena_reserve_pages(void *p__map, void *ptr__ign, u32 page_c
__bpf_kfunc_end_defs();
BTF_KFUNCS_START(arena_kfuncs)
-BTF_ID_FLAGS(func, bpf_arena_alloc_pages, KF_ARENA_RET | KF_ARENA_ARG2)
-BTF_ID_FLAGS(func, bpf_arena_free_pages, KF_ARENA_ARG2)
-BTF_ID_FLAGS(func, bpf_arena_reserve_pages, KF_ARENA_ARG2)
+BTF_ID_FLAGS(func, bpf_arena_alloc_pages, KF_ARENA_RET | KF_ARENA_ARG2 | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_arena_free_pages, KF_ARENA_ARG2 | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_arena_reserve_pages, KF_ARENA_ARG2 | KF_SPINLOCK_SAFE)
BTF_KFUNCS_END(arena_kfuncs)
static const struct btf_kfunc_id_set common_kfunc_set = {
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 4709a5ad0474..6388b6b23e49 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -4812,30 +4812,32 @@ BTF_ID_FLAGS(func, bpf_obj_drop, KF_RELEASE | KF_IMPLICIT_ARGS)
BTF_ID_FLAGS(func, bpf_obj_drop_impl, KF_RELEASE)
BTF_ID_FLAGS(func, bpf_percpu_obj_drop, KF_RELEASE | KF_IMPLICIT_ARGS)
BTF_ID_FLAGS(func, bpf_percpu_obj_drop_impl, KF_RELEASE)
-BTF_ID_FLAGS(func, bpf_refcount_acquire, KF_ACQUIRE | KF_RET_NULL | KF_RCU | KF_IMPLICIT_ARGS)
-BTF_ID_FLAGS(func, bpf_refcount_acquire_impl, KF_ACQUIRE | KF_RET_NULL | KF_RCU)
-BTF_ID_FLAGS(func, bpf_list_push_front, KF_IMPLICIT_ARGS)
-BTF_ID_FLAGS(func, bpf_list_push_front_impl)
-BTF_ID_FLAGS(func, bpf_list_push_back, KF_IMPLICIT_ARGS)
-BTF_ID_FLAGS(func, bpf_list_push_back_impl)
-BTF_ID_FLAGS(func, bpf_list_add, KF_IMPLICIT_ARGS)
-BTF_ID_FLAGS(func, bpf_list_pop_front, KF_ACQUIRE | KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_list_pop_back, KF_ACQUIRE | KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_list_del, KF_ACQUIRE | KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_list_front, KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_list_back, KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_list_is_first)
-BTF_ID_FLAGS(func, bpf_list_is_last)
-BTF_ID_FLAGS(func, bpf_list_empty)
+BTF_ID_FLAGS(func, bpf_refcount_acquire,
+ KF_ACQUIRE | KF_RET_NULL | KF_RCU | KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_refcount_acquire_impl,
+ KF_ACQUIRE | KF_RET_NULL | KF_RCU | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_push_front, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_push_front_impl, KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_push_back, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_push_back_impl, KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_add, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_pop_front, KF_ACQUIRE | KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_pop_back, KF_ACQUIRE | KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_del, KF_ACQUIRE | KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_front, KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_back, KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_is_first, KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_is_last, KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_list_empty, KF_SPINLOCK_SAFE)
BTF_ID_FLAGS(func, bpf_task_acquire, KF_ACQUIRE | KF_RCU | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_task_release, KF_RELEASE)
-BTF_ID_FLAGS(func, bpf_rbtree_remove, KF_ACQUIRE | KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_rbtree_add, KF_IMPLICIT_ARGS)
-BTF_ID_FLAGS(func, bpf_rbtree_add_impl)
-BTF_ID_FLAGS(func, bpf_rbtree_first, KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_rbtree_root, KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_rbtree_left, KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_rbtree_right, KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_rbtree_remove, KF_ACQUIRE | KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_rbtree_add, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_rbtree_add_impl, KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_rbtree_first, KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_rbtree_root, KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_rbtree_left, KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_rbtree_right, KF_RET_NULL | KF_SPINLOCK_SAFE)
#ifdef CONFIG_CGROUPS
BTF_ID_FLAGS(func, bpf_cgroup_acquire, KF_ACQUIRE | KF_RCU | KF_RET_NULL)
@@ -4885,9 +4887,9 @@ BTF_ID_FLAGS(func, bpf_rcu_read_lock)
BTF_ID_FLAGS(func, bpf_rcu_read_unlock)
BTF_ID_FLAGS(func, bpf_dynptr_slice, KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_dynptr_slice_rdwr, KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_iter_num_new, KF_ITER_NEW)
-BTF_ID_FLAGS(func, bpf_iter_num_next, KF_ITER_NEXT | KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_iter_num_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_iter_num_new, KF_ITER_NEW | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_iter_num_next, KF_ITER_NEXT | KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_iter_num_destroy, KF_ITER_DESTROY | KF_SPINLOCK_SAFE)
BTF_ID_FLAGS(func, bpf_iter_task_vma_new, KF_ITER_NEW | KF_RCU)
BTF_ID_FLAGS(func, bpf_iter_task_vma_next, KF_ITER_NEXT | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_iter_task_vma_destroy, KF_ITER_DESTROY)
@@ -4962,8 +4964,8 @@ BTF_ID_FLAGS(func, bpf_strncasestr);
#if defined(CONFIG_BPF_LSM) && defined(CONFIG_CGROUPS)
BTF_ID_FLAGS(func, bpf_cgroup_read_xattr, KF_RCU)
#endif
-BTF_ID_FLAGS(func, bpf_stream_vprintk, KF_IMPLICIT_ARGS)
-BTF_ID_FLAGS(func, bpf_stream_print_stack, KF_IMPLICIT_ARGS)
+BTF_ID_FLAGS(func, bpf_stream_vprintk, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_stream_print_stack, KF_IMPLICIT_ARGS | KF_SPINLOCK_SAFE)
BTF_ID_FLAGS(func, bpf_task_work_schedule_signal, KF_IMPLICIT_ARGS)
BTF_ID_FLAGS(func, bpf_task_work_schedule_resume, KF_IMPLICIT_ARGS)
BTF_ID_FLAGS(func, bpf_dynptr_from_file)
diff --git a/kernel/bpf/rqspinlock.c b/kernel/bpf/rqspinlock.c
index e4e338cdb437..e527cb425cf4 100644
--- a/kernel/bpf/rqspinlock.c
+++ b/kernel/bpf/rqspinlock.c
@@ -744,10 +744,10 @@ __bpf_kfunc void bpf_res_spin_unlock_irqrestore(struct bpf_res_spin_lock *lock,
__bpf_kfunc_end_defs();
BTF_KFUNCS_START(rqspinlock_kfunc_ids)
-BTF_ID_FLAGS(func, bpf_res_spin_lock, KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_res_spin_unlock)
-BTF_ID_FLAGS(func, bpf_res_spin_lock_irqsave, KF_RET_NULL)
-BTF_ID_FLAGS(func, bpf_res_spin_unlock_irqrestore)
+BTF_ID_FLAGS(func, bpf_res_spin_lock, KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_res_spin_unlock, KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_res_spin_lock_irqsave, KF_RET_NULL | KF_SPINLOCK_SAFE)
+BTF_ID_FLAGS(func, bpf_res_spin_unlock_irqrestore, KF_SPINLOCK_SAFE)
BTF_KFUNCS_END(rqspinlock_kfunc_ids)
static const struct btf_kfunc_id_set rqspinlock_kfunc_set = {
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9c1f8d552655..7c1edcae293a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11797,20 +11797,6 @@ static bool is_bpf_rbtree_api_kfunc(u32 btf_id)
btf_id == special_kfunc_list[KF_bpf_rbtree_right];
}
-static bool is_bpf_iter_num_api_kfunc(u32 btf_id)
-{
- return btf_id == special_kfunc_list[KF_bpf_iter_num_new] ||
- btf_id == special_kfunc_list[KF_bpf_iter_num_next] ||
- btf_id == special_kfunc_list[KF_bpf_iter_num_destroy];
-}
-
-static bool is_bpf_graph_api_kfunc(u32 btf_id)
-{
- return is_bpf_list_api_kfunc(btf_id) ||
- is_bpf_rbtree_api_kfunc(btf_id) ||
- is_bpf_refcount_acquire_kfunc(btf_id);
-}
-
static bool is_bpf_res_spin_lock_kfunc(u32 btf_id)
{
return btf_id == special_kfunc_list[KF_bpf_res_spin_lock] ||
@@ -11819,29 +11805,11 @@ static bool is_bpf_res_spin_lock_kfunc(u32 btf_id)
btf_id == special_kfunc_list[KF_bpf_res_spin_unlock_irqrestore];
}
-static bool is_bpf_arena_kfunc(u32 btf_id)
-{
- return btf_id == special_kfunc_list[KF_bpf_arena_alloc_pages] ||
- btf_id == special_kfunc_list[KF_bpf_arena_free_pages] ||
- btf_id == special_kfunc_list[KF_bpf_arena_reserve_pages];
-}
-
-static bool is_bpf_stream_kfunc(u32 btf_id)
-{
- return btf_id == special_kfunc_list[KF_bpf_stream_vprintk] ||
- btf_id == special_kfunc_list[KF_bpf_stream_print_stack];
-}
-
static bool kfunc_spin_allowed(struct bpf_verifier_env *env, s32 func_id, s16 offset)
{
struct bpf_kfunc_meta kfunc;
int err;
- if (is_bpf_graph_api_kfunc(func_id) || is_bpf_iter_num_api_kfunc(func_id) ||
- is_bpf_res_spin_lock_kfunc(func_id) || is_bpf_arena_kfunc(func_id) ||
- is_bpf_stream_kfunc(func_id))
- return true;
-
err = fetch_kfunc_meta(env, func_id, offset, &kfunc);
if (err || !kfunc.flags)
return false;
--
2.50.1 (Apple Git-155)
next prev parent reply other threads:[~2026-08-05 15:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-05 15:33 [PATCH bpf-next v2 0/3] bpf: Allow selected kfuncs under bpf_spin_lock Kaitao Cheng
2026-08-05 15:33 ` [PATCH bpf-next v2 1/3] bpf: Add KF_SPINLOCK_SAFE flag for " Kaitao Cheng
2026-08-05 15:33 ` Kaitao Cheng [this message]
2026-08-05 15:33 ` [PATCH bpf-next v2 3/3] selftests/bpf: Test module kfunc calls under spin lock Kaitao Cheng
2026-08-05 16:51 ` [PATCH bpf-next v2 0/3] bpf: Allow selected kfuncs under bpf_spin_lock Leon Hwang
2026-08-06 9:10 ` patchwork-bot+netdevbpf
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