Re: [PATCH bpf-next v3 2/2] selftests/bpf: Update kfuncs using btf_struct_meta to new variants

[Jiri Olsa <olsajiri@gmail.com>]

On Wed, Mar 18, 2026 at 04:42:10PM -0700, Ihor Solodrai wrote:
> Update selftests to use the new non-_impl kfuncs marked with
> KF_IMPLICIT_ARGS by removing redundant declarations and macros from
> bpf_experimental.h (the new kfuncs are present in the vmlinux.h) and
> updating relevant callsites.
> 
> Fix spin_lock verifier-log matching for lock_id_kptr_preserve by
> accepting variable instruction numbers. The calls to kfuncs with
> implicit arguments do not have register moves (e.g. r5 = 0)
> corresponding to dummy arguments anymore, so the order of instructions
> has shifted.
> 
> Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
> ---
>  .../testing/selftests/bpf/bpf_experimental.h  | 156 +-----------------
>  .../selftests/bpf/prog_tests/spin_lock.c      |   5 +-
>  .../selftests/bpf/progs/kptr_xchg_inline.c    |   4 +-
>  3 files changed, 9 insertions(+), 156 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
> index 44466acf8083..2234bd6bc9d3 100644
> --- a/tools/testing/selftests/bpf/bpf_experimental.h
> +++ b/tools/testing/selftests/bpf/bpf_experimental.h
> @@ -8,156 +8,11 @@
>  
>  #define __contains(name, node) __attribute__((btf_decl_tag("contains:" #name ":" #node)))
>  
> -/* Description
> - *	Allocates an object of the type represented by 'local_type_id' in
> - *	program BTF. User may use the bpf_core_type_id_local macro to pass the
> - *	type ID of a struct in program BTF.
> - *
> - *	The 'local_type_id' parameter must be a known constant.
> - *	The 'meta' parameter is rewritten by the verifier, no need for BPF
> - *	program to set it.
> - * Returns
> - *	A pointer to an object of the type corresponding to the passed in
> - *	'local_type_id', or NULL on failure.
> - */
> -extern void *bpf_obj_new_impl(__u64 local_type_id, void *meta) __ksym;
> -
> -/* Convenience macro to wrap over bpf_obj_new_impl */
> -#define bpf_obj_new(type) ((type *)bpf_obj_new_impl(bpf_core_type_id_local(type), NULL))
> -
> -/* Description
> - *	Free an allocated object. All fields of the object that require
> - *	destruction will be destructed before the storage is freed.
> - *
> - *	The 'meta' parameter is rewritten by the verifier, no need for BPF
> - *	program to set it.
> - * Returns
> - *	Void.
> - */
> -extern void bpf_obj_drop_impl(void *kptr, void *meta) __ksym;
> -
> -/* Convenience macro to wrap over bpf_obj_drop_impl */
> -#define bpf_obj_drop(kptr) bpf_obj_drop_impl(kptr, NULL)
> -
> -/* Description
> - *	Increment the refcount on a refcounted local kptr, turning the
> - *	non-owning reference input into an owning reference in the process.
> - *
> - *	The 'meta' parameter is rewritten by the verifier, no need for BPF
> - *	program to set it.
> - * Returns
> - *	An owning reference to the object pointed to by 'kptr'
> - */
> -extern void *bpf_refcount_acquire_impl(void *kptr, void *meta) __ksym;
> -
> -/* Convenience macro to wrap over bpf_refcount_acquire_impl */
> -#define bpf_refcount_acquire(kptr) bpf_refcount_acquire_impl(kptr, NULL)
> -
> -/* Description
> - *	Add a new entry to the beginning of the BPF linked list.
> - *
> - *	The 'meta' and 'off' parameters are rewritten by the verifier, no need
> - *	for BPF programs to set them
> - * Returns
> - *	0 if the node was successfully added
> - *	-EINVAL if the node wasn't added because it's already in a list
> - */
> -extern int bpf_list_push_front_impl(struct bpf_list_head *head,
> -				    struct bpf_list_node *node,
> -				    void *meta, __u64 off) __ksym;
> -
> -/* Convenience macro to wrap over bpf_list_push_front_impl */
> -#define bpf_list_push_front(head, node) bpf_list_push_front_impl(head, node, NULL, 0)
> -
> -/* Description
> - *	Add a new entry to the end of the BPF linked list.
> - *
> - *	The 'meta' and 'off' parameters are rewritten by the verifier, no need
> - *	for BPF programs to set them
> - * Returns
> - *	0 if the node was successfully added
> - *	-EINVAL if the node wasn't added because it's already in a list
> - */
> -extern int bpf_list_push_back_impl(struct bpf_list_head *head,
> -				   struct bpf_list_node *node,
> -				   void *meta, __u64 off) __ksym;
> -
> -/* Convenience macro to wrap over bpf_list_push_back_impl */
> -#define bpf_list_push_back(head, node) bpf_list_push_back_impl(head, node, NULL, 0)
> -
> -/* Description
> - *	Remove the entry at the beginning of the BPF linked list.
> - * Returns
> - *	Pointer to bpf_list_node of deleted entry, or NULL if list is empty.
> - */
> -extern struct bpf_list_node *bpf_list_pop_front(struct bpf_list_head *head) __ksym;
> -
> -/* Description
> - *	Remove the entry at the end of the BPF linked list.
> - * Returns
> - *	Pointer to bpf_list_node of deleted entry, or NULL if list is empty.
> - */
> -extern struct bpf_list_node *bpf_list_pop_back(struct bpf_list_head *head) __ksym;
> -
> -/* Description
> - *	Remove 'node' from rbtree with root 'root'
> - * Returns
> - * 	Pointer to the removed node, or NULL if 'root' didn't contain 'node'
> - */
> -extern struct bpf_rb_node *bpf_rbtree_remove(struct bpf_rb_root *root,
> -					     struct bpf_rb_node *node) __ksym;
> -
> -/* Description
> - *	Add 'node' to rbtree with root 'root' using comparator 'less'
> - *
> - *	The 'meta' and 'off' parameters are rewritten by the verifier, no need
> - *	for BPF programs to set them
> - * Returns
> - *	0 if the node was successfully added
> - *	-EINVAL if the node wasn't added because it's already in a tree
> - */
> -extern int bpf_rbtree_add_impl(struct bpf_rb_root *root, struct bpf_rb_node *node,
> -			       bool (less)(struct bpf_rb_node *a, const struct bpf_rb_node *b),
> -			       void *meta, __u64 off) __ksym;
> -
> -/* Convenience macro to wrap over bpf_rbtree_add_impl */
> -#define bpf_rbtree_add(head, node, less) bpf_rbtree_add_impl(head, node, less, NULL, 0)
> +/* Convenience macro to wrap over bpf_obj_new */
> +#define bpf_obj_new(type) ((type *)bpf_obj_new(bpf_core_type_id_local(type)))
>  
> -/* Description
> - *	Return the first (leftmost) node in input tree
> - * Returns
> - *	Pointer to the node, which is _not_ removed from the tree. If the tree
> - *	contains no nodes, returns NULL.
> - */
> -extern struct bpf_rb_node *bpf_rbtree_first(struct bpf_rb_root *root) __ksym;
> -
> -/* Description
> - *	Allocates a percpu object of the type represented by 'local_type_id' in
> - *	program BTF. User may use the bpf_core_type_id_local macro to pass the
> - *	type ID of a struct in program BTF.
> - *
> - *	The 'local_type_id' parameter must be a known constant.
> - *	The 'meta' parameter is rewritten by the verifier, no need for BPF
> - *	program to set it.
> - * Returns
> - *	A pointer to a percpu object of the type corresponding to the passed in
> - *	'local_type_id', or NULL on failure.
> - */
> -extern void *bpf_percpu_obj_new_impl(__u64 local_type_id, void *meta) __ksym;
> -
> -/* Convenience macro to wrap over bpf_percpu_obj_new_impl */
> -#define bpf_percpu_obj_new(type) ((type __percpu_kptr *)bpf_percpu_obj_new_impl(bpf_core_type_id_local(type), NULL))
> -
> -/* Description
> - *	Free an allocated percpu object. All fields of the object that require
> - *	destruction will be destructed before the storage is freed.
> - *
> - *	The 'meta' parameter is rewritten by the verifier, no need for BPF
> - *	program to set it.
> - * Returns
> - *	Void.
> - */
> -extern void bpf_percpu_obj_drop_impl(void *kptr, void *meta) __ksym;
> +/* Convenience macro to wrap over bpf_percpu_obj_new */
> +#define bpf_percpu_obj_new(type) ((type __percpu_kptr *)bpf_percpu_obj_new(bpf_core_type_id_local(type)))

nit, seems like a shame to remove all the comments which are still
valid, maybe we could leave those externs with comments and just
drop the _impl suffix

jirka