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Tue, 16 Dec 2025 16:32:11 -0800 (PST) Message-ID: <0b9fd098307b5aa15a7d7a3f7f2b01fe63e66a53.camel@gmail.com> Subject: Re: [PATCH bpf-next v9 05/10] libbpf: Verify BTF Sorting From: Eduard Zingerman To: Donglin Peng , ast@kernel.org, andrii.nakryiko@gmail.com Cc: zhangxiaoqin@xiaomi.com, ihor.solodrai@linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, pengdonglin , Alan Maguire Date: Tue, 16 Dec 2025 16:32:08 -0800 In-Reply-To: <20251208062353.1702672-6-dolinux.peng@gmail.com> References: <20251208062353.1702672-1-dolinux.peng@gmail.com> <20251208062353.1702672-6-dolinux.peng@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2025-12-08 at 14:23 +0800, Donglin Peng wrote: > From: pengdonglin >=20 > This patch checks whether the BTF is sorted by name in ascending > order. If sorted, binary search will be used when looking up types. >=20 > Cc: Eduard Zingerman > Cc: Alexei Starovoitov > Cc: Andrii Nakryiko > Cc: Alan Maguire > Cc: Ihor Solodrai > Cc: Xiaoqin Zhang > Signed-off-by: pengdonglin > --- > tools/lib/bpf/btf.c | 46 ++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 45 insertions(+), 1 deletion(-) >=20 > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c > index 7f150c869bf6..a53d24704857 100644 > --- a/tools/lib/bpf/btf.c > +++ b/tools/lib/bpf/btf.c > @@ -899,6 +899,49 @@ int btf__resolve_type(const struct btf *btf, __u32 t= ype_id) > return type_id; > } > =20 > +/* > + * Assuming that types are sorted by name in ascending order. > + */ > +static int btf_compare_type_names(const void *a, const void *b, void *pr= iv) This can be declared as ...(u32 a, u32 b, struct btf *btf). > +{ > + struct btf *btf =3D (struct btf *)priv; > + struct btf_type *ta =3D btf_type_by_id(btf, *(__u32 *)a); > + struct btf_type *tb =3D btf_type_by_id(btf, *(__u32 *)b); > + const char *na, *nb; > + > + na =3D btf__str_by_offset(btf, ta->name_off); > + nb =3D btf__str_by_offset(btf, tb->name_off); > + return strcmp(na, nb); > +} > + > +static void btf_check_sorted(struct btf *btf) > +{ > + const struct btf_type *t; > + int i, k =3D 0, n; > + __u32 sorted_start_id =3D 0; > + > + if (btf->nr_types < 2) > + return; > + > + n =3D btf__type_cnt(btf) - 1; > + for (i =3D btf->start_id; i < n; i++) { > + k =3D i + 1; > + if (btf_compare_type_names(&i, &k, btf) > 0) > + return; > + t =3D btf_type_by_id(btf, i); > + if (sorted_start_id =3D=3D 0 && > + !str_is_empty(btf__str_by_offset(btf, t->name_off))) ^^^^^^^^ Nit: broken indentation. > + sorted_start_id =3D i; > + } > + > + t =3D btf_type_by_id(btf, k); Nit: please use 'n' instead of 'k'. Maybe just change condition in the loop and avoid the second part? E.g.: n =3D btf__type_cnt(btf); for (...) { ... if (k < n && btf_compare_type_names(a: &i, b: &k, priv: btf) > 0) return; ... } A bit shorter/simpler this way. > + if (sorted_start_id =3D=3D 0 && > + !str_is_empty(btf__str_by_offset(btf, t->name_off))) > + sorted_start_id =3D k; > + if (sorted_start_id) > + btf->sorted_start_id =3D sorted_start_id; > +} > + > static __s32 btf_find_by_name_bsearch(const struct btf *btf, const char = *name, > __s32 start_id, __s32 end_id) > { > @@ -935,7 +978,7 @@ static __s32 btf_find_by_name_kind(const struct btf *= btf, int start_id, > =20 > if (start_id < btf->start_id) { > idx =3D btf_find_by_name_kind(btf->base_btf, start_id, > - type_name, kind); > + type_name, kind); Nit: shouldn't be in this patch. > if (idx >=3D 0) > return idx; > start_id =3D btf->start_id; > @@ -1147,6 +1190,7 @@ static struct btf *btf_new(const void *data, __u32 = size, struct btf *base_btf, b > err =3D err ?: btf_sanity_check(btf); > if (err) > goto done; > + btf_check_sorted(btf); > =20 > done: > if (err) {