| Message ID | 26ec519a00aa47f25bc6b4c7e4e15e5191ba4d45.1714430735.git.dxu@dxuuu.xyz (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | BPF |
| Headers | show |
| Series | pahole: Inject kfunc decl tags into BTF | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Mon, Apr 29, 2024 at 04:46:00PM -0600, Daniel Xu wrote: > This commit teaches pahole to parse symbols in .BTF_ids section in > vmlinux and discover exported kfuncs. Pahole then takes the list of > kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc. > > Example of encoding: > > $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l > 121 > > $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337 > [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static > [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1 > > This enables downstream users and tools to dynamically discover which > kfuncs are available on a system by parsing vmlinux or module BTF, both > available in /sys/kernel/btf. > > This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs. > > Acked-by: Jiri Olsa <jolsa@kernel.org> > Tested-by: Jiri Olsa <jolsa@kernel.org> > Reviewed-by: Alan Maguire <alan.maguire@oracle.com> > Tested-by: Alan Maguire <alan.maguire@oracle.com> > Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Here I needed this to avoid an strdup possibly followed by a free and then checking the strdup result, please Ack/revalidate tags. I'm dropping them as there are changes. - Arnaldo diff --git a/btf_encoder.c b/btf_encoder.c index e9d82e0af0e178fd..c2df2bc7a374447b 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -1434,11 +1434,13 @@ static char *get_func_name(const char *sym) return NULL; /* Strip prefix and handle malformed input such as __BTF_ID__func___ */ - func = strdup(sym + sizeof(BTF_ID_FUNC_PFX) - 1); - if (!strstr(func, "__")) { - free(func); + const char *func_sans_prefix = sym + sizeof(BTF_ID_FUNC_PFX) - 1; + if (!strstr(func_sans_prefix, "__")) return NULL; - } + + func = strdup(func_sans_prefix); + if (!func) + return NULL; /* Strip suffix */ end = strrchr(func, '_');
On Mon, Apr 29, 2024 at 04:46:00PM -0600, Daniel Xu wrote: > This commit teaches pahole to parse symbols in .BTF_ids section in > vmlinux and discover exported kfuncs. Pahole then takes the list of > kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc. > > Example of encoding: > > $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l > 121 > > $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337 > [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static > [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1 > > This enables downstream users and tools to dynamically discover which > kfuncs are available on a system by parsing vmlinux or module BTF, both > available in /sys/kernel/btf. > > This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs. I'm trying this but: ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux btf_encoder__tag_kfuncs(cgroup_rstat_updated): found=0 btf_encoder__tag_kfuncs(cgroup_rstat_flush): found=0 btf_encoder__tag_kfuncs(security_file_permission): found=0 btf_encoder__tag_kfuncs(security_inode_getattr): found=0 btf_encoder__tag_kfuncs(security_file_open): found=0 btf_encoder__tag_kfuncs(security_path_truncate): found=0 btf_encoder__tag_kfuncs(vfs_truncate): found=0 btf_encoder__tag_kfuncs(vfs_fallocate): found=0 btf_encoder__tag_kfuncs(dentry_open): found=0 btf_encoder__tag_kfuncs(vfs_getattr): found=0 btf_encoder__tag_kfuncs(filp_close): found=0 btf_encoder__tag_kfuncs(bpf_lookup_user_key): found=0 btf_encoder__tag_kfuncs(bpf_lookup_system_key): found=0 btf_encoder__tag_kfuncs(bpf_key_put): found=0 btf_encoder__tag_kfuncs(bpf_verify_pkcs7_signature): found=0 btf_encoder__tag_kfuncs(bpf_obj_new_impl): found=0 <SNIP all with found=0> With: ⬢[acme@toolbox pahole]$ git diff -U16 diff --git a/btf_encoder.c b/btf_encoder.c index c2df2bc7a374447b..27a16d6564381b60 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -1689,32 +1689,35 @@ static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder) func = get_func_name(name); if (!func) continue; /* Check if function belongs to a kfunc set */ ranges = gobuffer__entries(&btf_kfunc_ranges); ranges_cnt = gobuffer__nr_entries(&btf_kfunc_ranges); found = false; for (j = 0; j < ranges_cnt; j++) { size_t addr = sym.st_value; if (ranges[j].start <= addr && addr < ranges[j].end) { found = true; break; } } + + printf("%s(%s): found=%d\n", __func__, func, found); + if (!found) { free(func); continue; } err = btf_encoder__tag_kfunc(encoder, &btf_funcs, func); if (err) { fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, func); free(func); goto out; } free(func); } err = 0; out: -------------- The vmlinux I'm testing on has the kfuncs, etc, as we can see with: ⬢[acme@toolbox pahole]$ readelf -sW vmlinux | grep __BTF_ID__func__ | wc -l 517 ⬢[acme@toolbox pahole]$ readelf -sW vmlinux | grep __BTF_ID__func__ | tail 97887: ffffffff83266bfc 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_cong_avoid__805493 97888: ffffffff83266c04 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_state__806494 97889: ffffffff83266c0c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_cwnd_event__807495 97890: ffffffff83266c14 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_acked__808496 98068: ffffffff83266c24 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_ssthresh__773199 98069: ffffffff83266c2c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_cong_avoid__774200 98070: ffffffff83266c34 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_undo_cwnd__775201 98071: ffffffff83266c3c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_slow_start__776202 98072: ffffffff83266c44 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_cong_avoid_ai__777203 101522: ffffffff83266c5c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__update_socket_protocol__80024 ⬢[acme@toolbox pahole]$ So that btf_encoder__tag_kfuncs() isn't finding any? $ pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux btf_encoder__tag_kfuncs(vmlinux) Yeah, getting the source filename, the right one. Then is_sym_kfunc_set() never returns true... But: ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux is_sym_kfunc_set(__BTF_ID__set8__bpf_rstat_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__key_sig_kfunc_set, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__generic_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__common_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__bpf_map_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__cpumask_kfunc_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_syscall_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_skb, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_xdp, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_sock_addr, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__bpf_sk_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__xdp_metadata_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__bpf_test_modify_return_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__test_sk_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__tcp_cubic_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__bpf_tcp_ca_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) is_sym_kfunc_set(__BTF_ID__set8__bpf_mptcp_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) real 0m5.586s user 0m29.707s sys 0m2.160s ⬢[acme@toolbox pahole]$ And then: ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux is_sym_kfunc_set(__BTF_ID__set8__bpf_rstat_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__key_sig_kfunc_set, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__generic_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__common_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__bpf_map_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__cpumask_kfunc_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_syscall_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_skb, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_xdp, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_sock_addr, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__bpf_sk_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__xdp_metadata_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__bpf_test_modify_return_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__test_sk_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__tcp_cubic_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__bpf_tcp_ca_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) is_sym_kfunc_set(__BTF_ID__set8__bpf_mptcp_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) real 0m5.597s user 0m29.620s sys 0m2.138s ⬢[acme@toolbox pahole]$ Run out of time, I probably am using an old vmlinux, will try later with one generated from a current kernel, or maybe you guys point to my st00pidity saying what I am missing 8-) - Arnaldo
On Tue, Apr 30, 2024 at 05:42:14PM GMT, Arnaldo Carvalho de Melo wrote: > On Mon, Apr 29, 2024 at 04:46:00PM -0600, Daniel Xu wrote: > > This commit teaches pahole to parse symbols in .BTF_ids section in > > vmlinux and discover exported kfuncs. Pahole then takes the list of > > kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc. > > > > Example of encoding: > > > > $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l > > 121 > > > > $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337 > > [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static > > [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1 > > > > This enables downstream users and tools to dynamically discover which > > kfuncs are available on a system by parsing vmlinux or module BTF, both > > available in /sys/kernel/btf. > > > > This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs. > > I'm trying this but: > > ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > btf_encoder__tag_kfuncs(cgroup_rstat_updated): found=0 > btf_encoder__tag_kfuncs(cgroup_rstat_flush): found=0 > btf_encoder__tag_kfuncs(security_file_permission): found=0 > btf_encoder__tag_kfuncs(security_inode_getattr): found=0 > btf_encoder__tag_kfuncs(security_file_open): found=0 > btf_encoder__tag_kfuncs(security_path_truncate): found=0 > btf_encoder__tag_kfuncs(vfs_truncate): found=0 > btf_encoder__tag_kfuncs(vfs_fallocate): found=0 > btf_encoder__tag_kfuncs(dentry_open): found=0 > btf_encoder__tag_kfuncs(vfs_getattr): found=0 > btf_encoder__tag_kfuncs(filp_close): found=0 > btf_encoder__tag_kfuncs(bpf_lookup_user_key): found=0 > btf_encoder__tag_kfuncs(bpf_lookup_system_key): found=0 > btf_encoder__tag_kfuncs(bpf_key_put): found=0 > btf_encoder__tag_kfuncs(bpf_verify_pkcs7_signature): found=0 > btf_encoder__tag_kfuncs(bpf_obj_new_impl): found=0 > <SNIP all with found=0> > > With: > > ⬢[acme@toolbox pahole]$ git diff -U16 > diff --git a/btf_encoder.c b/btf_encoder.c > index c2df2bc7a374447b..27a16d6564381b60 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -1689,32 +1689,35 @@ static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder) > func = get_func_name(name); > if (!func) > continue; > > /* Check if function belongs to a kfunc set */ > ranges = gobuffer__entries(&btf_kfunc_ranges); > ranges_cnt = gobuffer__nr_entries(&btf_kfunc_ranges); > found = false; > for (j = 0; j < ranges_cnt; j++) { > size_t addr = sym.st_value; > > if (ranges[j].start <= addr && addr < ranges[j].end) { > found = true; > break; > } > } > + > + printf("%s(%s): found=%d\n", __func__, func, found); > + > if (!found) { > free(func); > continue; > } > > err = btf_encoder__tag_kfunc(encoder, &btf_funcs, func); > if (err) { > fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, func); > free(func); > goto out; > } > free(func); > } > > err = 0; > out: > > -------------- > > The vmlinux I'm testing on has the kfuncs, etc, as we can see with: > > ⬢[acme@toolbox pahole]$ readelf -sW vmlinux | grep __BTF_ID__func__ | wc -l > 517 > ⬢[acme@toolbox pahole]$ readelf -sW vmlinux | grep __BTF_ID__func__ | tail > 97887: ffffffff83266bfc 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_cong_avoid__805493 > 97888: ffffffff83266c04 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_state__806494 > 97889: ffffffff83266c0c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_cwnd_event__807495 > 97890: ffffffff83266c14 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_acked__808496 > 98068: ffffffff83266c24 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_ssthresh__773199 > 98069: ffffffff83266c2c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_cong_avoid__774200 > 98070: ffffffff83266c34 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_undo_cwnd__775201 > 98071: ffffffff83266c3c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_slow_start__776202 > 98072: ffffffff83266c44 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_cong_avoid_ai__777203 > 101522: ffffffff83266c5c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__update_socket_protocol__80024 > ⬢[acme@toolbox pahole]$ > > > So that btf_encoder__tag_kfuncs() isn't finding any? > > $ pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > btf_encoder__tag_kfuncs(vmlinux) > > Yeah, getting the source filename, the right one. > > Then is_sym_kfunc_set() never returns true... But: > > ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > is_sym_kfunc_set(__BTF_ID__set8__bpf_rstat_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__key_sig_kfunc_set, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__generic_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__common_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__bpf_map_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__cpumask_kfunc_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_syscall_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_skb, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_xdp, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_sock_addr, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__bpf_sk_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__xdp_metadata_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__bpf_test_modify_return_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__test_sk_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__tcp_cubic_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__bpf_tcp_ca_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > is_sym_kfunc_set(__BTF_ID__set8__bpf_mptcp_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > real 0m5.586s > user 0m29.707s > sys 0m2.160s > ⬢[acme@toolbox pahole]$ > > And then: > > ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > is_sym_kfunc_set(__BTF_ID__set8__bpf_rstat_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__key_sig_kfunc_set, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__generic_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__common_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__bpf_map_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__cpumask_kfunc_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_syscall_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_skb, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_xdp, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_sock_addr, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__bpf_sk_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__xdp_metadata_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__bpf_test_modify_return_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__test_sk_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__tcp_cubic_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__bpf_tcp_ca_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > is_sym_kfunc_set(__BTF_ID__set8__bpf_mptcp_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) set->flags=0 here is odd. I'd expect at least some of those to be non-zero. Can you check if your tree has https://github.com/torvalds/linux/commit/6f3189f38a3e995232e028a4c341164c4aca1b20 ? Thanks, Daniel
On Tue, Apr 30, 2024 at 04:57:26PM GMT, Arnaldo Carvalho de Melo wrote: > On Mon, Apr 29, 2024 at 04:46:00PM -0600, Daniel Xu wrote: > > This commit teaches pahole to parse symbols in .BTF_ids section in > > vmlinux and discover exported kfuncs. Pahole then takes the list of > > kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc. > > > > Example of encoding: > > > > $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l > > 121 > > > > $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337 > > [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static > > [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1 > > > > This enables downstream users and tools to dynamically discover which > > kfuncs are available on a system by parsing vmlinux or module BTF, both > > available in /sys/kernel/btf. > > > > This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs. > > > > Acked-by: Jiri Olsa <jolsa@kernel.org> > > Tested-by: Jiri Olsa <jolsa@kernel.org> > > Reviewed-by: Alan Maguire <alan.maguire@oracle.com> > > Tested-by: Alan Maguire <alan.maguire@oracle.com> > > Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> > > Here I needed this to avoid an strdup possibly followed by a free and > then checking the strdup result, please Ack/revalidate tags. I'm > dropping them as there are changes. > > - Arnaldo > > diff --git a/btf_encoder.c b/btf_encoder.c > index e9d82e0af0e178fd..c2df2bc7a374447b 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -1434,11 +1434,13 @@ static char *get_func_name(const char *sym) > return NULL; > > /* Strip prefix and handle malformed input such as __BTF_ID__func___ */ > - func = strdup(sym + sizeof(BTF_ID_FUNC_PFX) - 1); > - if (!strstr(func, "__")) { > - free(func); > + const char *func_sans_prefix = sym + sizeof(BTF_ID_FUNC_PFX) - 1; > + if (!strstr(func_sans_prefix, "__")) > return NULL; > - } > + > + func = strdup(func_sans_prefix); > + if (!func) > + return NULL; > > /* Strip suffix */ > end = strrchr(func, '_'); Thanks, that looks good to me. Please lemme know if I should re-spin. Otherwise, Acked-by: Daniel Xu <dxu@dxuuu.xyz>
On Tue, Apr 30, 2024 at 05:27:24PM -0600, Daniel Xu wrote: > On Tue, Apr 30, 2024 at 05:42:14PM GMT, Arnaldo Carvalho de Melo wrote: > > On Mon, Apr 29, 2024 at 04:46:00PM -0600, Daniel Xu wrote: > > > This commit teaches pahole to parse symbols in .BTF_ids section in > > > vmlinux and discover exported kfuncs. Pahole then takes the list of > > > kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc. > > > > > > Example of encoding: > > > > > > $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l > > > 121 > > > > > > $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337 > > > [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static > > > [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1 > > > > > > This enables downstream users and tools to dynamically discover which > > > kfuncs are available on a system by parsing vmlinux or module BTF, both > > > available in /sys/kernel/btf. > > > > > > This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs. > > > > I'm trying this but: > > > > ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > > btf_encoder__tag_kfuncs(cgroup_rstat_updated): found=0 > > btf_encoder__tag_kfuncs(cgroup_rstat_flush): found=0 > > btf_encoder__tag_kfuncs(security_file_permission): found=0 > > btf_encoder__tag_kfuncs(security_inode_getattr): found=0 > > btf_encoder__tag_kfuncs(security_file_open): found=0 > > btf_encoder__tag_kfuncs(security_path_truncate): found=0 > > btf_encoder__tag_kfuncs(vfs_truncate): found=0 > > btf_encoder__tag_kfuncs(vfs_fallocate): found=0 > > btf_encoder__tag_kfuncs(dentry_open): found=0 > > btf_encoder__tag_kfuncs(vfs_getattr): found=0 > > btf_encoder__tag_kfuncs(filp_close): found=0 > > btf_encoder__tag_kfuncs(bpf_lookup_user_key): found=0 > > btf_encoder__tag_kfuncs(bpf_lookup_system_key): found=0 > > btf_encoder__tag_kfuncs(bpf_key_put): found=0 > > btf_encoder__tag_kfuncs(bpf_verify_pkcs7_signature): found=0 > > btf_encoder__tag_kfuncs(bpf_obj_new_impl): found=0 > > <SNIP all with found=0> > > > > With: > > > > ⬢[acme@toolbox pahole]$ git diff -U16 > > diff --git a/btf_encoder.c b/btf_encoder.c > > index c2df2bc7a374447b..27a16d6564381b60 100644 > > --- a/btf_encoder.c > > +++ b/btf_encoder.c > > @@ -1689,32 +1689,35 @@ static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder) > > func = get_func_name(name); > > if (!func) > > continue; > > > > /* Check if function belongs to a kfunc set */ > > ranges = gobuffer__entries(&btf_kfunc_ranges); > > ranges_cnt = gobuffer__nr_entries(&btf_kfunc_ranges); > > found = false; > > for (j = 0; j < ranges_cnt; j++) { > > size_t addr = sym.st_value; > > > > if (ranges[j].start <= addr && addr < ranges[j].end) { > > found = true; > > break; > > } > > } > > + > > + printf("%s(%s): found=%d\n", __func__, func, found); > > + > > if (!found) { > > free(func); > > continue; > > } > > > > err = btf_encoder__tag_kfunc(encoder, &btf_funcs, func); > > if (err) { > > fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, func); > > free(func); > > goto out; > > } > > free(func); > > } > > > > err = 0; > > out: > > > > -------------- > > > > The vmlinux I'm testing on has the kfuncs, etc, as we can see with: > > > > ⬢[acme@toolbox pahole]$ readelf -sW vmlinux | grep __BTF_ID__func__ | wc -l > > 517 > > ⬢[acme@toolbox pahole]$ readelf -sW vmlinux | grep __BTF_ID__func__ | tail > > 97887: ffffffff83266bfc 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_cong_avoid__805493 > > 97888: ffffffff83266c04 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_state__806494 > > 97889: ffffffff83266c0c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_cwnd_event__807495 > > 97890: ffffffff83266c14 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_acked__808496 > > 98068: ffffffff83266c24 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_ssthresh__773199 > > 98069: ffffffff83266c2c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_cong_avoid__774200 > > 98070: ffffffff83266c34 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_undo_cwnd__775201 > > 98071: ffffffff83266c3c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_slow_start__776202 > > 98072: ffffffff83266c44 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_cong_avoid_ai__777203 > > 101522: ffffffff83266c5c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__update_socket_protocol__80024 > > ⬢[acme@toolbox pahole]$ > > > > > > So that btf_encoder__tag_kfuncs() isn't finding any? > > > > $ pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > > btf_encoder__tag_kfuncs(vmlinux) > > > > Yeah, getting the source filename, the right one. > > > > Then is_sym_kfunc_set() never returns true... But: > > > > ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > > is_sym_kfunc_set(__BTF_ID__set8__bpf_rstat_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__key_sig_kfunc_set, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__generic_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__common_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_map_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__cpumask_kfunc_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_syscall_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_skb, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_xdp, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_sock_addr, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_sk_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__xdp_metadata_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_test_modify_return_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__test_sk_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__tcp_cubic_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_tcp_ca_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_mptcp_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > > real 0m5.586s > > user 0m29.707s > > sys 0m2.160s > > ⬢[acme@toolbox pahole]$ > > > > And then: > > > > ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > > is_sym_kfunc_set(__BTF_ID__set8__bpf_rstat_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__key_sig_kfunc_set, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__generic_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__common_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_map_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__cpumask_kfunc_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_syscall_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_skb, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_xdp, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_sock_addr, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_sk_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__xdp_metadata_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_test_modify_return_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__test_sk_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__tcp_cubic_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_tcp_ca_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > is_sym_kfunc_set(__BTF_ID__set8__bpf_mptcp_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > set->flags=0 here is odd. I'd expect at least some of those to be > non-zero. Can you check if your tree has > https://github.com/torvalds/linux/commit/6f3189f38a3e995232e028a4c341164c4aca1b20 > ? ⬢[acme@toolbox linux]$ git tag --contains 6f3189f38a3e995232e028a4c341164c4aca1b20 v6.9-rc1 v6.9-rc2 v6.9-rc3 v6.9-rc4 v6.9-rc5 v6.9-rc6 v6.9-rc7 ⬢[acme@toolbox linux]$ git log --oneline -1 dd5a440a31fae6e4 (HEAD, tag: v6.9-rc7, torvalds/master) Linux 6.9-rc7 ⬢[acme@toolbox linux]$ So now with a just built upstream kernel I get the output below, do you have patches for other tools to consume this? Or does, say, bpftrace already handles such decl tags, etc? I think I'll make pfunct (its in the pahole git repo) to consume it: ⬢[acme@toolbox pahole]$ pfunct --help Usage: pfunct [OPTION...] FILE -a, --addr=ADDR show just the function that where ADDR is -b, --expand_types Expand types needed by the prototype --compile[=FUNCTION] Generate compilable source code with types expanded (Default all functions) -c, --class=CLASS functions that have CLASS pointer parameters -E, --externals show just external functions -f, --function=FUNCTION show just FUNCTION -F, --format_path=FORMAT_LIST List of debugging formats to try -g, --goto_labels show number of goto labels -G, --cc_uninlined declared inline, uninlined by compiler -H, --cc_inlined not declared inline, inlined by compiler -i, --inline_expansions show inline expansions -I, --inline_expansions_stats show inline expansions stats -l, --decl_info show source code info --no_parm_names Don't show parameter names -N, --function_name_len show size of functions names -p, --nr_parms show number of parameters -P, --prototypes show function prototypes --symtab[=NAME] show symbol table NAME (Default .symtab) -s, --sizes show size of functions -S, --nr_variables show number of variables -t, --total_inline_stats show Multi-CU total inline expansions stats -T, --variables show variables -V, --verbose be verbose -?, --help Give this help list --usage Give a short usage message --version Print program version Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options. ⬢[acme@toolbox pahole]$ - Arnaldo ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux-v6.9.0-rc7 real 0m5.938s user 0m32.050s sys 0m2.075s ⬢[acme@toolbox pahole]$ bpftool btf dump file vmlinux.btf.decl_tag,decl_tag_kfuncs | grep -w 94151 [94151] FUNC 'cgroup_rstat_updated' type_id=94150 linkage=static [135450] DECL_TAG 'bpf_kfunc' type_id=94151 component_idx=-1 ⬢[acme@toolbox pahole]$ bpftool btf dump file vmlinux.btf.decl_tag,decl_tag_kfuncs | grep -w 94150 -A2 [94150] FUNC_PROTO '(anon)' ret_type_id=0 vlen=2 'cgrp' type_id=744 'cpu' type_id=12 [94151] FUNC 'cgroup_rstat_updated' type_id=94150 linkage=static [94152] STRUCT 'pids_cgroup' size=288 vlen=6 'css' type_id=1786 bits_offset=0 ⬢[acme@toolbox pahole]$ ⬢[acme@toolbox pahole]$ bpftool btf dump file vmlinux.btf.decl_tag,decl_tag_kfuncs | grep DECL 'BTF_KIND_DECL_TAG' val=17 [135450] DECL_TAG 'bpf_kfunc' type_id=94151 component_idx=-1 [135451] DECL_TAG 'bpf_kfunc' type_id=94146 component_idx=-1 [135452] DECL_TAG 'bpf_kfunc' type_id=74311 component_idx=-1 [135453] DECL_TAG 'bpf_kfunc' type_id=74309 component_idx=-1 [135454] DECL_TAG 'bpf_kfunc' type_id=74307 component_idx=-1 [135455] DECL_TAG 'bpf_kfunc' type_id=74305 component_idx=-1 [135456] DECL_TAG 'bpf_kfunc' type_id=74302 component_idx=-1 [135457] DECL_TAG 'bpf_kfunc' type_id=43681 component_idx=-1 [135458] DECL_TAG 'bpf_kfunc' type_id=83157 component_idx=-1 [135459] DECL_TAG 'bpf_kfunc' type_id=83156 component_idx=-1 [135460] DECL_TAG 'bpf_kfunc' type_id=83152 component_idx=-1 [135461] DECL_TAG 'bpf_kfunc' type_id=83151 component_idx=-1 [135462] DECL_TAG 'bpf_kfunc' type_id=83149 component_idx=-1 [135463] DECL_TAG 'bpf_kfunc' type_id=83145 component_idx=-1 [135464] DECL_TAG 'bpf_kfunc' type_id=83144 component_idx=-1 [135465] DECL_TAG 'bpf_kfunc' type_id=83142 component_idx=-1 [135466] DECL_TAG 'bpf_kfunc' type_id=83141 component_idx=-1 [135467] DECL_TAG 'bpf_kfunc' type_id=83133 component_idx=-1 [135468] DECL_TAG 'bpf_kfunc' type_id=83132 component_idx=-1 [135469] DECL_TAG 'bpf_kfunc' type_id=83139 component_idx=-1 [135470] DECL_TAG 'bpf_kfunc' type_id=83137 component_idx=-1 [135471] DECL_TAG 'bpf_kfunc' type_id=83135 component_idx=-1 [135472] DECL_TAG 'bpf_kfunc' type_id=83130 component_idx=-1 [135473] DECL_TAG 'bpf_kfunc' type_id=83128 component_idx=-1 [135474] DECL_TAG 'bpf_kfunc' type_id=83125 component_idx=-1 [135475] DECL_TAG 'bpf_kfunc' type_id=83123 component_idx=-1 [135476] DECL_TAG 'bpf_kfunc' type_id=83121 component_idx=-1 [135477] DECL_TAG 'bpf_kfunc' type_id=83119 component_idx=-1 [135478] DECL_TAG 'bpf_kfunc' type_id=83117 component_idx=-1 [135479] DECL_TAG 'bpf_kfunc' type_id=83095 component_idx=-1 [135480] DECL_TAG 'bpf_kfunc' type_id=83103 component_idx=-1 [135481] DECL_TAG 'bpf_kfunc' type_id=83101 component_idx=-1 [135482] DECL_TAG 'bpf_kfunc' type_id=83099 component_idx=-1 [135483] DECL_TAG 'bpf_kfunc' type_id=83098 component_idx=-1 [135484] DECL_TAG 'bpf_kfunc' type_id=83115 component_idx=-1 [135485] DECL_TAG 'bpf_kfunc' type_id=83114 component_idx=-1 [135486] DECL_TAG 'bpf_kfunc' type_id=24936 component_idx=-1 [135487] DECL_TAG 'bpf_kfunc' type_id=24934 component_idx=-1 [135488] DECL_TAG 'bpf_kfunc' type_id=24932 component_idx=-1 [135489] DECL_TAG 'bpf_kfunc' type_id=35395 component_idx=-1 [135490] DECL_TAG 'bpf_kfunc' type_id=35393 component_idx=-1 [135491] DECL_TAG 'bpf_kfunc' type_id=35391 component_idx=-1 [135492] DECL_TAG 'bpf_kfunc' type_id=35389 component_idx=-1 [135493] DECL_TAG 'bpf_kfunc' type_id=35387 component_idx=-1 [135494] DECL_TAG 'bpf_kfunc' type_id=35385 component_idx=-1 [135495] DECL_TAG 'bpf_kfunc' type_id=129497 component_idx=-1 [135496] DECL_TAG 'bpf_kfunc' type_id=129495 component_idx=-1 [135497] DECL_TAG 'bpf_kfunc' type_id=129493 component_idx=-1 [135498] DECL_TAG 'bpf_kfunc' type_id=35383 component_idx=-1 [135499] DECL_TAG 'bpf_kfunc' type_id=35381 component_idx=-1 [135500] DECL_TAG 'bpf_kfunc' type_id=35379 component_idx=-1 [135501] DECL_TAG 'bpf_kfunc' type_id=83112 component_idx=-1 [135502] DECL_TAG 'bpf_kfunc' type_id=83110 component_idx=-1 [135503] DECL_TAG 'bpf_kfunc' type_id=83109 component_idx=-1 [135504] DECL_TAG 'bpf_kfunc' type_id=83107 component_idx=-1 [135505] DECL_TAG 'bpf_kfunc' type_id=83105 component_idx=-1 [135506] DECL_TAG 'bpf_kfunc' type_id=129409 component_idx=-1 [135507] DECL_TAG 'bpf_kfunc' type_id=119719 component_idx=-1 [135508] DECL_TAG 'bpf_kfunc' type_id=119717 component_idx=-1 [135509] DECL_TAG 'bpf_kfunc' type_id=83434 component_idx=-1 [135510] DECL_TAG 'bpf_kfunc' type_id=83430 component_idx=-1 [135511] DECL_TAG 'bpf_kfunc' type_id=83432 component_idx=-1 [135512] DECL_TAG 'bpf_kfunc' type_id=83427 component_idx=-1 [135513] DECL_TAG 'bpf_kfunc' type_id=83426 component_idx=-1 [135514] DECL_TAG 'bpf_kfunc' type_id=83425 component_idx=-1 [135515] DECL_TAG 'bpf_kfunc' type_id=83424 component_idx=-1 [135516] DECL_TAG 'bpf_kfunc' type_id=83423 component_idx=-1 [135517] DECL_TAG 'bpf_kfunc' type_id=83421 component_idx=-1 [135518] DECL_TAG 'bpf_kfunc' type_id=83419 component_idx=-1 [135519] DECL_TAG 'bpf_kfunc' type_id=83418 component_idx=-1 [135520] DECL_TAG 'bpf_kfunc' type_id=83416 component_idx=-1 [135521] DECL_TAG 'bpf_kfunc' type_id=83415 component_idx=-1 [135522] DECL_TAG 'bpf_kfunc' type_id=83413 component_idx=-1 [135523] DECL_TAG 'bpf_kfunc' type_id=83411 component_idx=-1 [135524] DECL_TAG 'bpf_kfunc' type_id=83410 component_idx=-1 [135525] DECL_TAG 'bpf_kfunc' type_id=83408 component_idx=-1 [135526] DECL_TAG 'bpf_kfunc' type_id=83407 component_idx=-1 [135527] DECL_TAG 'bpf_kfunc' type_id=83406 component_idx=-1 [135528] DECL_TAG 'bpf_kfunc' type_id=83404 component_idx=-1 [135529] DECL_TAG 'bpf_kfunc' type_id=83403 component_idx=-1 [135530] DECL_TAG 'bpf_kfunc' type_id=83401 component_idx=-1 [135531] DECL_TAG 'bpf_kfunc' type_id=83399 component_idx=-1 [135532] DECL_TAG 'bpf_kfunc' type_id=83398 component_idx=-1 [135533] DECL_TAG 'bpf_kfunc' type_id=83396 component_idx=-1 [135534] DECL_TAG 'bpf_kfunc' type_id=84592 component_idx=-1 [135535] DECL_TAG 'bpf_kfunc' type_id=78862 component_idx=-1 [135536] DECL_TAG 'bpf_kfunc' type_id=78855 component_idx=-1 [135537] DECL_TAG 'bpf_kfunc' type_id=78853 component_idx=-1 [135538] DECL_TAG 'bpf_kfunc' type_id=78851 component_idx=-1 [135539] DECL_TAG 'bpf_kfunc' type_id=78849 component_idx=-1 [135540] DECL_TAG 'bpf_kfunc' type_id=52826 component_idx=-1 [135541] DECL_TAG 'bpf_kfunc' type_id=52825 component_idx=-1 [135542] DECL_TAG 'bpf_kfunc' type_id=52823 component_idx=-1 [135543] DECL_TAG 'bpf_kfunc' type_id=52821 component_idx=-1 [135544] DECL_TAG 'bpf_kfunc' type_id=52816 component_idx=-1 [135545] DECL_TAG 'bpf_kfunc' type_id=79148 component_idx=-1 [135546] DECL_TAG 'bpf_kfunc' type_id=79146 component_idx=-1 [135547] DECL_TAG 'bpf_kfunc' type_id=79144 component_idx=-1 [135548] DECL_TAG 'bpf_kfunc' type_id=33070 component_idx=-1 [135549] DECL_TAG 'bpf_kfunc' type_id=33068 component_idx=-1 [135550] DECL_TAG 'bpf_kfunc' type_id=33088 component_idx=-1 [135551] DECL_TAG 'bpf_kfunc' type_id=33064 component_idx=-1 [135552] DECL_TAG 'bpf_kfunc' type_id=33061 component_idx=-1 [135553] DECL_TAG 'bpf_kfunc' type_id=134975 component_idx=-1 [135554] DECL_TAG 'bpf_kfunc' type_id=134971 component_idx=-1 [135555] DECL_TAG 'bpf_kfunc' type_id=134972 component_idx=-1 [135556] DECL_TAG 'bpf_kfunc' type_id=134970 component_idx=-1 [135557] DECL_TAG 'bpf_kfunc' type_id=134974 component_idx=-1 [135558] DECL_TAG 'bpf_kfunc' type_id=134969 component_idx=-1 [135559] DECL_TAG 'bpf_kfunc' type_id=53825 component_idx=-1 [135560] DECL_TAG 'bpf_kfunc' type_id=53827 component_idx=-1 [135561] DECL_TAG 'bpf_kfunc' type_id=53824 component_idx=-1 [135562] DECL_TAG 'bpf_kfunc' type_id=53831 component_idx=-1 [135563] DECL_TAG 'bpf_kfunc' type_id=53829 component_idx=-1 [135564] DECL_TAG 'bpf_kfunc' type_id=21317 component_idx=-1 [135565] DECL_TAG 'bpf_kfunc' type_id=21315 component_idx=-1 ⬢[acme@toolbox pahole]$
On Mon, May 06, 2024 at 05:07:54PM GMT, Arnaldo Carvalho de Melo wrote: > On Tue, Apr 30, 2024 at 05:27:24PM -0600, Daniel Xu wrote: > > On Tue, Apr 30, 2024 at 05:42:14PM GMT, Arnaldo Carvalho de Melo wrote: > > > On Mon, Apr 29, 2024 at 04:46:00PM -0600, Daniel Xu wrote: > > > > This commit teaches pahole to parse symbols in .BTF_ids section in > > > > vmlinux and discover exported kfuncs. Pahole then takes the list of > > > > kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc. > > > > > > > > Example of encoding: > > > > > > > > $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l > > > > 121 > > > > > > > > $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337 > > > > [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static > > > > [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1 > > > > > > > > This enables downstream users and tools to dynamically discover which > > > > kfuncs are available on a system by parsing vmlinux or module BTF, both > > > > available in /sys/kernel/btf. > > > > > > > > This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs. > > > > > > I'm trying this but: > > > > > > ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > > > btf_encoder__tag_kfuncs(cgroup_rstat_updated): found=0 > > > btf_encoder__tag_kfuncs(cgroup_rstat_flush): found=0 > > > btf_encoder__tag_kfuncs(security_file_permission): found=0 > > > btf_encoder__tag_kfuncs(security_inode_getattr): found=0 > > > btf_encoder__tag_kfuncs(security_file_open): found=0 > > > btf_encoder__tag_kfuncs(security_path_truncate): found=0 > > > btf_encoder__tag_kfuncs(vfs_truncate): found=0 > > > btf_encoder__tag_kfuncs(vfs_fallocate): found=0 > > > btf_encoder__tag_kfuncs(dentry_open): found=0 > > > btf_encoder__tag_kfuncs(vfs_getattr): found=0 > > > btf_encoder__tag_kfuncs(filp_close): found=0 > > > btf_encoder__tag_kfuncs(bpf_lookup_user_key): found=0 > > > btf_encoder__tag_kfuncs(bpf_lookup_system_key): found=0 > > > btf_encoder__tag_kfuncs(bpf_key_put): found=0 > > > btf_encoder__tag_kfuncs(bpf_verify_pkcs7_signature): found=0 > > > btf_encoder__tag_kfuncs(bpf_obj_new_impl): found=0 > > > <SNIP all with found=0> > > > > > > With: > > > > > > ⬢[acme@toolbox pahole]$ git diff -U16 > > > diff --git a/btf_encoder.c b/btf_encoder.c > > > index c2df2bc7a374447b..27a16d6564381b60 100644 > > > --- a/btf_encoder.c > > > +++ b/btf_encoder.c > > > @@ -1689,32 +1689,35 @@ static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder) > > > func = get_func_name(name); > > > if (!func) > > > continue; > > > > > > /* Check if function belongs to a kfunc set */ > > > ranges = gobuffer__entries(&btf_kfunc_ranges); > > > ranges_cnt = gobuffer__nr_entries(&btf_kfunc_ranges); > > > found = false; > > > for (j = 0; j < ranges_cnt; j++) { > > > size_t addr = sym.st_value; > > > > > > if (ranges[j].start <= addr && addr < ranges[j].end) { > > > found = true; > > > break; > > > } > > > } > > > + > > > + printf("%s(%s): found=%d\n", __func__, func, found); > > > + > > > if (!found) { > > > free(func); > > > continue; > > > } > > > > > > err = btf_encoder__tag_kfunc(encoder, &btf_funcs, func); > > > if (err) { > > > fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, func); > > > free(func); > > > goto out; > > > } > > > free(func); > > > } > > > > > > err = 0; > > > out: > > > > > > -------------- > > > > > > The vmlinux I'm testing on has the kfuncs, etc, as we can see with: > > > > > > ⬢[acme@toolbox pahole]$ readelf -sW vmlinux | grep __BTF_ID__func__ | wc -l > > > 517 > > > ⬢[acme@toolbox pahole]$ readelf -sW vmlinux | grep __BTF_ID__func__ | tail > > > 97887: ffffffff83266bfc 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_cong_avoid__805493 > > > 97888: ffffffff83266c04 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_state__806494 > > > 97889: ffffffff83266c0c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_cwnd_event__807495 > > > 97890: ffffffff83266c14 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__cubictcp_acked__808496 > > > 98068: ffffffff83266c24 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_ssthresh__773199 > > > 98069: ffffffff83266c2c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_cong_avoid__774200 > > > 98070: ffffffff83266c34 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_reno_undo_cwnd__775201 > > > 98071: ffffffff83266c3c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_slow_start__776202 > > > 98072: ffffffff83266c44 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__tcp_cong_avoid_ai__777203 > > > 101522: ffffffff83266c5c 4 OBJECT LOCAL DEFAULT 15 __BTF_ID__func__update_socket_protocol__80024 > > > ⬢[acme@toolbox pahole]$ > > > > > > > > > So that btf_encoder__tag_kfuncs() isn't finding any? > > > > > > $ pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > > > btf_encoder__tag_kfuncs(vmlinux) > > > > > > Yeah, getting the source filename, the right one. > > > > > > Then is_sym_kfunc_set() never returns true... But: > > > > > > ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_rstat_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__key_sig_kfunc_set, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__generic_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__common_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_map_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__cpumask_kfunc_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_syscall_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_skb, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_xdp, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_sock_addr, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_sk_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__xdp_metadata_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_test_modify_return_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__test_sk_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__tcp_cubic_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_tcp_ca_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_mptcp_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__) > > > > > > real 0m5.586s > > > user 0m29.707s > > > sys 0m2.160s > > > ⬢[acme@toolbox pahole]$ > > > > > > And then: > > > > > > ⬢[acme@toolbox pahole]$ time pahole -j --btf_features=decl_tag,decl_tag_kfuncs --btf_encode_detached=vmlinux.btf.decl_tag,decl_tag_kfuncs vmlinux > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_rstat_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__key_sig_kfunc_set, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__generic_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__common_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_map_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__cpumask_kfunc_btf_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__hid_bpf_syscall_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_skb, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_xdp, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_kfunc_check_set_sock_addr, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_sk_iter_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__xdp_metadata_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_test_modify_return_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__test_sk_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__tcp_cubic_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_tcp_ca_check_kfunc_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > is_sym_kfunc_set(__BTF_ID__set8__bpf_mptcp_fmodret_ids, BTF_ID_SET8_PFX=__BTF_ID__set8__, set->flags= 0, BTF_SET8_KFUNCS=1, ret=0) > > > > set->flags=0 here is odd. I'd expect at least some of those to be > > non-zero. Can you check if your tree has > > https://github.com/torvalds/linux/commit/6f3189f38a3e995232e028a4c341164c4aca1b20 > > ? > > ⬢[acme@toolbox linux]$ git tag --contains 6f3189f38a3e995232e028a4c341164c4aca1b20 > v6.9-rc1 > v6.9-rc2 > v6.9-rc3 > v6.9-rc4 > v6.9-rc5 > v6.9-rc6 > v6.9-rc7 > ⬢[acme@toolbox linux]$ git log --oneline -1 > dd5a440a31fae6e4 (HEAD, tag: v6.9-rc7, torvalds/master) Linux 6.9-rc7 > ⬢[acme@toolbox linux]$ > > So now with a just built upstream kernel I get the output below, do you > have patches for other tools to consume this? Or does, say, bpftrace > already handles such decl tags, etc? Yep, I have v3 of https://lore.kernel.org/bpf/cover.1707080349.git.dxu@dxuuu.xyz/ ready to send. The step after that bpftool patch is merged is teach/simplify the bpf selftests. Long term once all the changes propagate, it'll make bpf programmers workflows more efficient too. bpftrace will probably make use of these tags in the future. We are still working on our kfunc story (not supported yet). [..] > [135552] DECL_TAG 'bpf_kfunc' type_id=33061 component_idx=-1 > [135553] DECL_TAG 'bpf_kfunc' type_id=134975 component_idx=-1 > [135554] DECL_TAG 'bpf_kfunc' type_id=134971 component_idx=-1 > [135555] DECL_TAG 'bpf_kfunc' type_id=134972 component_idx=-1 > [135556] DECL_TAG 'bpf_kfunc' type_id=134970 component_idx=-1 > [135557] DECL_TAG 'bpf_kfunc' type_id=134974 component_idx=-1 > [135558] DECL_TAG 'bpf_kfunc' type_id=134969 component_idx=-1 > [135559] DECL_TAG 'bpf_kfunc' type_id=53825 component_idx=-1 > [135560] DECL_TAG 'bpf_kfunc' type_id=53827 component_idx=-1 > [135561] DECL_TAG 'bpf_kfunc' type_id=53824 component_idx=-1 > [135562] DECL_TAG 'bpf_kfunc' type_id=53831 component_idx=-1 > [135563] DECL_TAG 'bpf_kfunc' type_id=53829 component_idx=-1 > [135564] DECL_TAG 'bpf_kfunc' type_id=21317 component_idx=-1 > [135565] DECL_TAG 'bpf_kfunc' type_id=21315 component_idx=-1 > ⬢[acme@toolbox pahole]$ Glad it works! Thanks, Daniel
diff --git a/btf_encoder.c b/btf_encoder.c index f0ef20a..6cb0c8f 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -34,6 +34,21 @@ #include <pthread.h> #define BTF_ENCODER_MAX_PROTO 512 +#define BTF_IDS_SECTION ".BTF_ids" +#define BTF_ID_FUNC_PFX "__BTF_ID__func__" +#define BTF_ID_SET8_PFX "__BTF_ID__set8__" +#define BTF_SET8_KFUNCS (1 << 0) +#define BTF_KFUNC_TYPE_TAG "bpf_kfunc" + +/* Adapted from include/linux/btf_ids.h */ +struct btf_id_set8 { + uint32_t cnt; + uint32_t flags; + struct { + uint32_t id; + uint32_t flags; + } pairs[]; +}; /* state used to do later encoding of saved functions */ struct btf_encoder_state { @@ -76,6 +91,7 @@ struct btf_encoder { verbose, force, gen_floats, + skip_encoding_decl_tag, tag_kfuncs, is_rel; uint32_t array_index_id; @@ -95,6 +111,17 @@ struct btf_encoder { } functions; }; +struct btf_func { + const char *name; + int type_id; +}; + +/* Half open interval representing range of addresses containing kfuncs */ +struct btf_kfunc_set_range { + uint64_t start; + uint64_t end; +}; + static LIST_HEAD(encoders); static pthread_mutex_t encoders__lock = PTHREAD_MUTEX_INITIALIZER; @@ -1364,8 +1391,343 @@ out: return err; } +/* Returns if `sym` points to a kfunc set */ +static int is_sym_kfunc_set(GElf_Sym *sym, const char *name, Elf_Data *idlist, size_t idlist_addr) +{ + void *ptr = idlist->d_buf; + struct btf_id_set8 *set; + int off; + + /* kfuncs are only found in BTF_SET8's */ + if (!strstarts(name, BTF_ID_SET8_PFX)) + return false; + + off = sym->st_value - idlist_addr; + if (off >= idlist->d_size) { + fprintf(stderr, "%s: symbol '%s' out of bounds\n", __func__, name); + return false; + } + + /* Check the set8 flags to see if it was marked as kfunc */ + set = ptr + off; + return set->flags & BTF_SET8_KFUNCS; +} + +/* + * Parse BTF_ID symbol and return the func name. + * + * Returns: + * Caller-owned string containing func name if successful. + * NULL if !func or on error. + */ +static char *get_func_name(const char *sym) +{ + char *func, *end; + + /* Example input: __BTF_ID__func__vfs_close__1 + * + * The goal is to strip the prefix and suffix such that we only + * return vfs_close. + */ + + if (!strstarts(sym, BTF_ID_FUNC_PFX)) + return NULL; + + /* Strip prefix and handle malformed input such as __BTF_ID__func___ */ + func = strdup(sym + sizeof(BTF_ID_FUNC_PFX) - 1); + if (!strstr(func, "__")) { + free(func); + return NULL; + } + + /* Strip suffix */ + end = strrchr(func, '_'); + if (!end || *(end - 1) != '_') { + free(func); + return NULL; + } + *(end - 1) = '\0'; + + return func; +} + +static int btf_func_cmp(const void *_a, const void *_b) +{ + const struct btf_func *a = _a; + const struct btf_func *b = _b; + + return strcmp(a->name, b->name); +} + +/* + * Collects all functions described in BTF. + * Returns non-zero on error. + */ +static int btf_encoder__collect_btf_funcs(struct btf_encoder *encoder, struct gobuffer *funcs) +{ + struct btf *btf = encoder->btf; + int nr_types, type_id; + int err = -1; + + /* First collect all the func entries into an array */ + nr_types = btf__type_cnt(btf); + for (type_id = 1; type_id < nr_types; type_id++) { + const struct btf_type *type; + struct btf_func func = {}; + const char *name; + + type = btf__type_by_id(btf, type_id); + if (!type) { + fprintf(stderr, "%s: malformed BTF, can't resolve type for ID %d\n", + __func__, type_id); + err = -EINVAL; + goto out; + } + + if (!btf_is_func(type)) + continue; + + name = btf__name_by_offset(btf, type->name_off); + if (!name) { + fprintf(stderr, "%s: malformed BTF, can't resolve name for ID %d\n", + __func__, type_id); + err = -EINVAL; + goto out; + } + + func.name = name; + func.type_id = type_id; + err = gobuffer__add(funcs, &func, sizeof(func)); + if (err < 0) + goto out; + } + + /* Now that we've collected funcs, sort them by name */ + gobuffer__sort(funcs, sizeof(struct btf_func), btf_func_cmp); + + err = 0; +out: + return err; +} + +static int btf_encoder__tag_kfunc(struct btf_encoder *encoder, struct gobuffer *funcs, const char *kfunc) +{ + struct btf_func key = { .name = kfunc }; + struct btf *btf = encoder->btf; + struct btf_func *target; + const void *base; + unsigned int cnt; + int err = -1; + + base = gobuffer__entries(funcs); + cnt = gobuffer__nr_entries(funcs); + target = bsearch(&key, base, cnt, sizeof(key), btf_func_cmp); + if (!target) { + fprintf(stderr, "%s: failed to find kfunc '%s' in BTF\n", __func__, kfunc); + goto out; + } + + /* Note we are unconditionally adding the btf_decl_tag even + * though vmlinux may already contain btf_decl_tags for kfuncs. + * We are ok to do this b/c we will later btf__dedup() to remove + * any duplicates. + */ + err = btf__add_decl_tag(btf, BTF_KFUNC_TYPE_TAG, target->type_id, -1); + if (err < 0) { + fprintf(stderr, "%s: failed to insert kfunc decl tag for '%s': %d\n", + __func__, kfunc, err); + goto out; + } + + err = 0; +out: + return err; +} + +static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder) +{ + const char *filename = encoder->source_filename; + struct gobuffer btf_kfunc_ranges = {}; + struct gobuffer btf_funcs = {}; + Elf_Data *symbols = NULL; + Elf_Data *idlist = NULL; + Elf_Scn *symscn = NULL; + int symbols_shndx = -1; + size_t idlist_addr = 0; + int fd = -1, err = -1; + int idlist_shndx = -1; + size_t strtabidx = 0; + Elf_Scn *scn = NULL; + Elf *elf = NULL; + GElf_Shdr shdr; + size_t strndx; + char *secname; + int nr_syms; + int i = 0; + + fd = open(filename, O_RDONLY); + if (fd < 0) { + fprintf(stderr, "Cannot open %s\n", filename); + goto out; + } + + if (elf_version(EV_CURRENT) == EV_NONE) { + elf_error("Cannot set libelf version"); + goto out; + } + + elf = elf_begin(fd, ELF_C_READ, NULL); + if (elf == NULL) { + elf_error("Cannot update ELF file"); + goto out; + } + + /* Locate symbol table and .BTF_ids sections */ + if (elf_getshdrstrndx(elf, &strndx) < 0) + goto out; + + while ((scn = elf_nextscn(elf, scn)) != NULL) { + Elf_Data *data; + + i++; + if (!gelf_getshdr(scn, &shdr)) { + elf_error("Failed to get ELF section(%d) hdr", i); + goto out; + } + + secname = elf_strptr(elf, strndx, shdr.sh_name); + if (!secname) { + elf_error("Failed to get ELF section(%d) hdr name", i); + goto out; + } + + data = elf_getdata(scn, 0); + if (!data) { + elf_error("Failed to get ELF section(%d) data", i); + goto out; + } + + if (shdr.sh_type == SHT_SYMTAB) { + symbols_shndx = i; + symscn = scn; + symbols = data; + strtabidx = shdr.sh_link; + } else if (!strcmp(secname, BTF_IDS_SECTION)) { + idlist_shndx = i; + idlist_addr = shdr.sh_addr; + idlist = data; + } + } + + /* Cannot resolve symbol or .BTF_ids sections. Nothing to do. */ + if (symbols_shndx == -1 || idlist_shndx == -1) { + err = 0; + goto out; + } + + if (!gelf_getshdr(symscn, &shdr)) { + elf_error("Failed to get ELF symbol table header"); + goto out; + } + nr_syms = shdr.sh_size / shdr.sh_entsize; + + err = btf_encoder__collect_btf_funcs(encoder, &btf_funcs); + if (err) { + fprintf(stderr, "%s: failed to collect BTF funcs\n", __func__); + goto out; + } + + /* First collect all kfunc set ranges. + * + * Note we choose not to sort these ranges and accept a linear + * search when doing lookups. Reasoning is that the number of + * sets is ~O(100) and not worth the additional code to optimize. + */ + for (i = 0; i < nr_syms; i++) { + struct btf_kfunc_set_range range = {}; + const char *name; + GElf_Sym sym; + + if (!gelf_getsym(symbols, i, &sym)) { + elf_error("Failed to get ELF symbol(%d)", i); + goto out; + } + + if (sym.st_shndx != idlist_shndx) + continue; + + name = elf_strptr(elf, strtabidx, sym.st_name); + if (!is_sym_kfunc_set(&sym, name, idlist, idlist_addr)) + continue; + + range.start = sym.st_value; + range.end = sym.st_value + sym.st_size; + gobuffer__add(&btf_kfunc_ranges, &range, sizeof(range)); + } + + /* Now inject BTF with kfunc decl tag for detected kfuncs */ + for (i = 0; i < nr_syms; i++) { + const struct btf_kfunc_set_range *ranges; + unsigned int ranges_cnt; + char *func, *name; + GElf_Sym sym; + bool found; + int err; + int j; + + if (!gelf_getsym(symbols, i, &sym)) { + elf_error("Failed to get ELF symbol(%d)", i); + goto out; + } + + if (sym.st_shndx != idlist_shndx) + continue; + + name = elf_strptr(elf, strtabidx, sym.st_name); + func = get_func_name(name); + if (!func) + continue; + + /* Check if function belongs to a kfunc set */ + ranges = gobuffer__entries(&btf_kfunc_ranges); + ranges_cnt = gobuffer__nr_entries(&btf_kfunc_ranges); + found = false; + for (j = 0; j < ranges_cnt; j++) { + size_t addr = sym.st_value; + + if (ranges[j].start <= addr && addr < ranges[j].end) { + found = true; + break; + } + } + if (!found) { + free(func); + continue; + } + + err = btf_encoder__tag_kfunc(encoder, &btf_funcs, func); + if (err) { + fprintf(stderr, "%s: failed to tag kfunc '%s'\n", __func__, func); + free(func); + goto out; + } + free(func); + } + + err = 0; +out: + __gobuffer__delete(&btf_funcs); + __gobuffer__delete(&btf_kfunc_ranges); + if (elf) + elf_end(elf); + if (fd != -1) + close(fd); + return err; +} + int btf_encoder__encode(struct btf_encoder *encoder) { + bool should_tag_kfuncs; int err; /* for single-threaded case, saved funcs are added here */ @@ -1378,6 +1740,15 @@ int btf_encoder__encode(struct btf_encoder *encoder) if (btf__type_cnt(encoder->btf) == 1) return 0; + /* Note vmlinux may already contain btf_decl_tag's for kfuncs. So + * take care to call this before btf_dedup(). + */ + should_tag_kfuncs = encoder->tag_kfuncs && !encoder->skip_encoding_decl_tag; + if (should_tag_kfuncs && btf_encoder__tag_kfuncs(encoder)) { + fprintf(stderr, "%s: failed to tag kfuncs!\n", __func__); + return -1; + } + if (btf__dedup(encoder->btf, NULL)) { fprintf(stderr, "%s: btf__dedup failed!\n", __func__); return -1; @@ -1662,6 +2033,7 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam encoder->force = conf_load->btf_encode_force; encoder->gen_floats = conf_load->btf_gen_floats; encoder->skip_encoding_vars = conf_load->skip_encoding_btf_vars; + encoder->skip_encoding_decl_tag = conf_load->skip_encoding_btf_decl_tag; encoder->tag_kfuncs = conf_load->btf_decl_tag_kfuncs; encoder->verbose = verbose; encoder->has_index_type = false;
This commit teaches pahole to parse symbols in .BTF_ids section in vmlinux and discover exported kfuncs. Pahole then takes the list of kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc. Example of encoding: $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l 121 $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337 [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1 This enables downstream users and tools to dynamically discover which kfuncs are available on a system by parsing vmlinux or module BTF, both available in /sys/kernel/btf. This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs. Acked-by: Jiri Olsa <jolsa@kernel.org> Tested-by: Jiri Olsa <jolsa@kernel.org> Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Tested-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> --- btf_encoder.c | 372 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 372 insertions(+)