| Message ID | 20220628160127.607834-3-deso@posteo.net (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 633e7ceb2cbbae9b2f5ca69106b0de65728c5988 |
| Delegated to: | BPF |
| Headers | show |
| Series | Introduce type match support | expand |
2022-06-28 16:01 UTC+0000 ~ Daniel Müller <deso@posteo.net> > bpftool needs to know about the newly introduced BPF_CORE_TYPE_MATCHES > relocation for its 'gen min_core_btf' command to work properly in the > present of this relocation. > Specifically, we need to make sure to mark types and fields so that they > are present in the minimized BTF for "type match" checks to work out. > However, contrary to the existing btfgen_record_field_relo, we need to > rely on the BTF -- and not the spec -- to find fields. With this change > we handle this new variant correctly. The functionality will be tested > with follow on changes to BPF selftests, which already run against a > minimized BTF created with bpftool. > > Cc: Quentin Monnet <quentin@isovalent.com> > Signed-off-by: Daniel Müller <deso@posteo.net> Acked-by: Quentin Monnet <quentin@isovalent.com> Thanks!
On Tue, Jun 28, 2022 at 9:01 AM Daniel Müller <deso@posteo.net> wrote: > > bpftool needs to know about the newly introduced BPF_CORE_TYPE_MATCHES > relocation for its 'gen min_core_btf' command to work properly in the > present of this relocation. > Specifically, we need to make sure to mark types and fields so that they > are present in the minimized BTF for "type match" checks to work out. > However, contrary to the existing btfgen_record_field_relo, we need to > rely on the BTF -- and not the spec -- to find fields. With this change > we handle this new variant correctly. The functionality will be tested > with follow on changes to BPF selftests, which already run against a > minimized BTF created with bpftool. > > Cc: Quentin Monnet <quentin@isovalent.com> > Signed-off-by: Daniel Müller <deso@posteo.net> > --- > tools/bpf/bpftool/gen.c | 108 ++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 108 insertions(+) > > diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c > index 480cbd8..a30328c 100644 > --- a/tools/bpf/bpftool/gen.c > +++ b/tools/bpf/bpftool/gen.c > @@ -1856,6 +1856,112 @@ static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_sp > return 0; > } > > +/* Mark types, members, and member types. Compared to btfgen_record_field_relo, > + * this function does not rely on the target spec for inferring members, but > + * uses the associated BTF. > + * > + * The `behind_ptr` argument is used to stop marking of composite types reached > + * through a pointer. This way, we can keep BTF size in check while providing > + * reasonable match semantics. > + */ > +static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr) > +{ > + const struct btf_type *btf_type; > + struct btf *btf = info->src_btf; > + struct btf_type *cloned_type; > + int i, err; > + > + if (type_id == 0) > + return 0; > + > + btf_type = btf__type_by_id(btf, type_id); > + /* mark type on cloned BTF as used */ > + cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id); > + cloned_type->name_off = MARKED; > + > + switch (btf_kind(btf_type)) { > + case BTF_KIND_UNKN: > + case BTF_KIND_INT: > + case BTF_KIND_FLOAT: > + case BTF_KIND_ENUM: > + case BTF_KIND_ENUM64: > + break; > + case BTF_KIND_STRUCT: > + case BTF_KIND_UNION: { > + struct btf_member *m = btf_members(btf_type); > + __u16 vlen = btf_vlen(btf_type); > + > + if (behind_ptr) > + break; > + > + for (i = 0; i < vlen; i++, m++) { > + /* mark member */ > + btfgen_mark_member(info, type_id, i); > + > + /* mark member's type */ > + err = btfgen_mark_type_match(info, m->type, false); > + if (err) > + return err; > + } > + break; > + } > + case BTF_KIND_CONST: > + case BTF_KIND_FWD: > + case BTF_KIND_RESTRICT: > + case BTF_KIND_TYPEDEF: > + case BTF_KIND_VOLATILE: > + return btfgen_mark_type_match(info, btf_type->type, false); this should have preserved behind_ptr instead of resetting it to false (i.e. `const struct blah *` should be treated similarly to `struct blah *`). I've fixed it up while applying. > + case BTF_KIND_PTR: > + return btfgen_mark_type_match(info, btf_type->type, true); > + case BTF_KIND_ARRAY: { > + struct btf_array *array; > + > + array = btf_array(btf_type); > + /* mark array type */ > + err = btfgen_mark_type_match(info, array->type, false); > + /* mark array's index type */ > + err = err ? : btfgen_mark_type_match(info, array->index_type, false); > + if (err) > + return err; > + break; [...]
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index 480cbd8..a30328c 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -1856,6 +1856,112 @@ static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_sp return 0; } +/* Mark types, members, and member types. Compared to btfgen_record_field_relo, + * this function does not rely on the target spec for inferring members, but + * uses the associated BTF. + * + * The `behind_ptr` argument is used to stop marking of composite types reached + * through a pointer. This way, we can keep BTF size in check while providing + * reasonable match semantics. + */ +static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr) +{ + const struct btf_type *btf_type; + struct btf *btf = info->src_btf; + struct btf_type *cloned_type; + int i, err; + + if (type_id == 0) + return 0; + + btf_type = btf__type_by_id(btf, type_id); + /* mark type on cloned BTF as used */ + cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id); + cloned_type->name_off = MARKED; + + switch (btf_kind(btf_type)) { + case BTF_KIND_UNKN: + case BTF_KIND_INT: + case BTF_KIND_FLOAT: + case BTF_KIND_ENUM: + case BTF_KIND_ENUM64: + break; + case BTF_KIND_STRUCT: + case BTF_KIND_UNION: { + struct btf_member *m = btf_members(btf_type); + __u16 vlen = btf_vlen(btf_type); + + if (behind_ptr) + break; + + for (i = 0; i < vlen; i++, m++) { + /* mark member */ + btfgen_mark_member(info, type_id, i); + + /* mark member's type */ + err = btfgen_mark_type_match(info, m->type, false); + if (err) + return err; + } + break; + } + case BTF_KIND_CONST: + case BTF_KIND_FWD: + case BTF_KIND_RESTRICT: + case BTF_KIND_TYPEDEF: + case BTF_KIND_VOLATILE: + return btfgen_mark_type_match(info, btf_type->type, false); + case BTF_KIND_PTR: + return btfgen_mark_type_match(info, btf_type->type, true); + case BTF_KIND_ARRAY: { + struct btf_array *array; + + array = btf_array(btf_type); + /* mark array type */ + err = btfgen_mark_type_match(info, array->type, false); + /* mark array's index type */ + err = err ? : btfgen_mark_type_match(info, array->index_type, false); + if (err) + return err; + break; + } + case BTF_KIND_FUNC_PROTO: { + __u16 vlen = btf_vlen(btf_type); + struct btf_param *param; + + /* mark ret type */ + err = btfgen_mark_type_match(info, btf_type->type, false); + if (err) + return err; + + /* mark parameters types */ + param = btf_params(btf_type); + for (i = 0; i < vlen; i++) { + err = btfgen_mark_type_match(info, param->type, false); + if (err) + return err; + param++; + } + break; + } + /* tells if some other type needs to be handled */ + default: + p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id); + return -EINVAL; + } + + return 0; +} + +/* Mark types, members, and member types. Compared to btfgen_record_field_relo, + * this function does not rely on the target spec for inferring members, but + * uses the associated BTF. + */ +static int btfgen_record_type_match_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec) +{ + return btfgen_mark_type_match(info, targ_spec->root_type_id, false); +} + static int btfgen_record_type_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec) { return btfgen_mark_type(info, targ_spec->root_type_id, true); @@ -1882,6 +1988,8 @@ static int btfgen_record_reloc(struct btfgen_info *info, struct bpf_core_spec *r case BPF_CORE_TYPE_EXISTS: case BPF_CORE_TYPE_SIZE: return btfgen_record_type_relo(info, res); + case BPF_CORE_TYPE_MATCHES: + return btfgen_record_type_match_relo(info, res); case BPF_CORE_ENUMVAL_EXISTS: case BPF_CORE_ENUMVAL_VALUE: return btfgen_record_enumval_relo(info, res);
bpftool needs to know about the newly introduced BPF_CORE_TYPE_MATCHES relocation for its 'gen min_core_btf' command to work properly in the present of this relocation. Specifically, we need to make sure to mark types and fields so that they are present in the minimized BTF for "type match" checks to work out. However, contrary to the existing btfgen_record_field_relo, we need to rely on the BTF -- and not the spec -- to find fields. With this change we handle this new variant correctly. The functionality will be tested with follow on changes to BPF selftests, which already run against a minimized BTF created with bpftool. Cc: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Daniel Müller <deso@posteo.net> --- tools/bpf/bpftool/gen.c | 108 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+)