On Fri, 2025-02-21 at 02:09 +0800, Tao Chen wrote:
[...]
> Hi Eduard,
>
> I try to run your test case, but it seems btf_is_decl_tag always return
> false, Are there any special restrictions for the tag feature of btf？
Hi Tao,
> My compilation environment：
>
> pahole --version
> v1.29
> clang --version
> Ubuntu clang version 18.1.3 (1ubuntu1)
Hm, pahole should generate kfunc tags since 1.27.
I use pahole 'next' branch, but it is the same as 1.29 at the moment.
Do you see kfunc prototypes at the bottom of vmlinux.h?
They look like so:
...
extern u32 tcp_reno_undo_cwnd(struct sock *sk) __weak __ksym;
...
These are generated by bpftool from decl tags I look for in the test case.
Decl tags are inserted by pahole, see btf_encoder.c:btf_encoder__tag_kfuncs().
Anyways, below is the list of all kfuncs from my config,
it is possible to adapt the test case with something like this:
for (i = 0; i < ARRAY_SIZE(all_kfuncs); ++i) {
kfunc = all_kfuncs[i];
kfunc_id = btf__find_by_name_kind(vmlinux_btf, kfunc, BTF_KIND_FUNC);
printf("%-42s ", kfunc);
if (kfunc_id < 0) {
printf("<not found>\n");
continue;
}
...
}
--- 8< --------------------------------------
static const char *all_kfuncs[] = {
"bbr_cwnd_event",
"bbr_init",
"bbr_main",
"bbr_min_tso_segs",
"bbr_set_state",
"bbr_sndbuf_expand",
"bbr_ssthresh",
"bbr_undo_cwnd",
"bpf_arena_alloc_pages",
"bpf_arena_free_pages",
"bpf_cast_to_kern_ctx",
"bpf_cgroup_acquire",
"bpf_cgroup_ancestor",
"bpf_cgroup_from_id",
"bpf_cgroup_release",
"bpf_copy_from_user_str",
"bpf_cpumask_acquire",
"bpf_cpumask_and",
"bpf_cpumask_any_and_distribute",
"bpf_cpumask_any_distribute",
"bpf_cpumask_clear",
"bpf_cpumask_clear_cpu",
"bpf_cpumask_copy",
"bpf_cpumask_create",
"bpf_cpumask_empty",
"bpf_cpumask_equal",
"bpf_cpumask_first",
"bpf_cpumask_first_and",
"bpf_cpumask_first_zero",
"bpf_cpumask_full",
"bpf_cpumask_intersects",
"bpf_cpumask_or",
"bpf_cpumask_release",
"bpf_cpumask_set_cpu",
"bpf_cpumask_setall",
"bpf_cpumask_subset",
"bpf_cpumask_test_and_clear_cpu",
"bpf_cpumask_test_and_set_cpu",
"bpf_cpumask_test_cpu",
"bpf_cpumask_weight",
"bpf_cpumask_xor",
"bpf_crypto_ctx_acquire",
"bpf_crypto_ctx_create",
"bpf_crypto_ctx_release",
"bpf_crypto_decrypt",
"bpf_crypto_encrypt",
"bpf_ct_change_status",
"bpf_ct_change_timeout",
"bpf_ct_insert_entry",
"bpf_ct_release",
"bpf_ct_set_nat_info",
"bpf_ct_set_status",
"bpf_ct_set_timeout",
"bpf_dynptr_adjust",
"bpf_dynptr_clone",
"bpf_dynptr_from_skb",
"bpf_dynptr_from_xdp",
"bpf_dynptr_is_null",
"bpf_dynptr_is_rdonly",
"bpf_dynptr_size",
"bpf_dynptr_slice",
"bpf_dynptr_slice_rdwr",
"bpf_fentry_test1",
"bpf_get_dentry_xattr",
"bpf_get_file_xattr",
"bpf_get_fsverity_digest",
"bpf_get_kmem_cache",
"bpf_get_task_exe_file",
"bpf_iter_bits_destroy",
"bpf_iter_bits_new",
"bpf_iter_bits_next",
"bpf_iter_css_destroy",
"bpf_iter_css_new",
"bpf_iter_css_next",
"bpf_iter_css_task_destroy",
"bpf_iter_css_task_new",
"bpf_iter_css_task_next",
"bpf_iter_kmem_cache_destroy",
"bpf_iter_kmem_cache_new",
"bpf_iter_kmem_cache_next",
"bpf_iter_num_destroy",
"bpf_iter_num_new",
"bpf_iter_num_next",
"bpf_iter_scx_dsq_destroy",
"bpf_iter_scx_dsq_new",
"bpf_iter_scx_dsq_next",
"bpf_iter_task_destroy",
"bpf_iter_task_new",
"bpf_iter_task_next",
"bpf_iter_task_vma_destroy",
"bpf_iter_task_vma_new",
"bpf_iter_task_vma_next",
"bpf_key_put",
"bpf_kfunc_call_memb_release",
"bpf_kfunc_call_test_release",
"bpf_list_pop_back",
"bpf_list_pop_front",
"bpf_list_push_back_impl",
"bpf_list_push_front_impl",
"bpf_local_irq_restore",
"bpf_local_irq_save",
"bpf_lookup_system_key",
"bpf_lookup_user_key",
"bpf_map_sum_elem_count",
"bpf_modify_return_test",
"bpf_modify_return_test2",
"bpf_modify_return_test_tp",
"bpf_obj_drop_impl",
"bpf_obj_new_impl",
"bpf_path_d_path",
"bpf_percpu_obj_drop_impl",
"bpf_percpu_obj_new_impl",
"bpf_preempt_disable",
"bpf_preempt_enable",
"bpf_put_file",
"bpf_rbtree_add_impl",
"bpf_rbtree_first",
"bpf_rbtree_remove",
"bpf_rcu_read_lock",
"bpf_rcu_read_unlock",
"bpf_rdonly_cast",
"bpf_refcount_acquire_impl",
"bpf_remove_dentry_xattr",
"bpf_send_signal_task",
"bpf_session_cookie",
"bpf_session_is_return",
"bpf_set_dentry_xattr",
"bpf_sk_assign_tcp_reqsk",
"bpf_skb_ct_alloc",
"bpf_skb_ct_lookup",
"bpf_skb_get_fou_encap",
"bpf_skb_get_xfrm_info",
"bpf_skb_set_fou_encap",
"bpf_skb_set_xfrm_info",
"bpf_sock_addr_set_sun_path",
"bpf_sock_destroy",
"bpf_task_acquire",
"bpf_task_from_pid",
"bpf_task_from_vpid",
"bpf_task_get_cgroup1",
"bpf_task_release",
"bpf_task_under_cgroup",
"bpf_throw",
"bpf_verify_pkcs7_signature",
"bpf_wq_init",
"bpf_wq_set_callback_impl",
"bpf_wq_start",
"bpf_xdp_ct_alloc",
"bpf_xdp_ct_lookup",
"bpf_xdp_flow_lookup",
"bpf_xdp_get_xfrm_state",
"bpf_xdp_metadata_rx_hash",
"bpf_xdp_metadata_rx_timestamp",
"bpf_xdp_metadata_rx_vlan_tag",
"bpf_xdp_xfrm_state_release",
"cgroup_rstat_flush",
"cgroup_rstat_updated",
"crash_kexec",
"cubictcp_acked",
"cubictcp_cong_avoid",
"cubictcp_cwnd_event",
"cubictcp_init",
"cubictcp_recalc_ssthresh",
"cubictcp_state",
"dctcp_cwnd_event",
"dctcp_cwnd_undo",
"dctcp_init",
"dctcp_ssthresh",
"dctcp_state",
"dctcp_update_alpha",
"scx_bpf_consume",
"scx_bpf_cpu_rq",
"scx_bpf_cpuperf_cap",
"scx_bpf_cpuperf_cur",
"scx_bpf_cpuperf_set",
"scx_bpf_create_dsq",
"scx_bpf_destroy_dsq",
"scx_bpf_dispatch",
"scx_bpf_dispatch_cancel",
"scx_bpf_dispatch_from_dsq",
"scx_bpf_dispatch_from_dsq_set_slice",
"scx_bpf_dispatch_from_dsq_set_vtime",
"scx_bpf_dispatch_nr_slots",
"scx_bpf_dispatch_vtime",
"scx_bpf_dispatch_vtime_from_dsq",
"scx_bpf_dsq_insert",
"scx_bpf_dsq_insert_vtime",
"scx_bpf_dsq_move",
"scx_bpf_dsq_move_set_slice",
"scx_bpf_dsq_move_set_vtime",
"scx_bpf_dsq_move_to_local",
"scx_bpf_dsq_move_vtime",
"scx_bpf_dsq_nr_queued",
"scx_bpf_dump_bstr",
"scx_bpf_error_bstr",
"scx_bpf_exit_bstr",
"scx_bpf_get_idle_cpumask",
"scx_bpf_get_idle_smtmask",
"scx_bpf_get_online_cpumask",
"scx_bpf_get_possible_cpumask",
"scx_bpf_kick_cpu",
"scx_bpf_now",
"scx_bpf_nr_cpu_ids",
"scx_bpf_pick_any_cpu",
"scx_bpf_pick_idle_cpu",
"scx_bpf_put_cpumask",
"scx_bpf_put_idle_cpumask",
"scx_bpf_reenqueue_local",
"scx_bpf_select_cpu_dfl",
"scx_bpf_task_cgroup",
"scx_bpf_task_cpu",
"scx_bpf_task_running",
"scx_bpf_test_and_clear_cpu_idle",
"tcp_cong_avoid_ai",
"tcp_reno_cong_avoid",
"tcp_reno_ssthresh",
"tcp_reno_undo_cwnd",
"tcp_slow_start",
};
-------------------------------------- >8 ---
[...]
