From b35f14f410416f06ec54d187dedc372405757290 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 12 Mar 2020 11:50:33 -0700 Subject: [PATCH] libbpf: Split BTF presence checks into libbpf- and kernel-specific parts Needs for application BTF being present differs between user-space libbpf needs and kernel needs. Currently, BTF is mandatory only in kernel only when BPF application is using STRUCT_OPS. While libbpf itself relies more heavily on presense of BTF: - for BTF-defined maps; - for Kconfig externs; - for STRUCT_OPS as well. Thus, checks for presence and validness of bpf_object's BPF needs to be performed separately, which is patch does. Fixes: 5327644614a1 ("libbpf: Relax check whether BTF is mandatory") Reported-by: Michal Rostecki Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Martin KaFai Lau Cc: Quentin Monnet Link: https://lore.kernel.org/bpf/20200312185033.736911-1-andriin@fb.com --- tools/lib/bpf/libbpf.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 223be01dc466..1a787a2faf58 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -2284,9 +2284,16 @@ static void bpf_object__sanitize_btf_ext(struct bpf_object *obj) } } -static bool bpf_object__is_btf_mandatory(const struct bpf_object *obj) +static bool libbpf_needs_btf(const struct bpf_object *obj) { - return obj->efile.st_ops_shndx >= 0 || obj->nr_extern > 0; + return obj->efile.btf_maps_shndx >= 0 || + obj->efile.st_ops_shndx >= 0 || + obj->nr_extern > 0; +} + +static bool kernel_needs_btf(const struct bpf_object *obj) +{ + return obj->efile.st_ops_shndx >= 0; } static int bpf_object__init_btf(struct bpf_object *obj, @@ -2322,7 +2329,7 @@ static int bpf_object__init_btf(struct bpf_object *obj, } } out: - if (err && bpf_object__is_btf_mandatory(obj)) { + if (err && libbpf_needs_btf(obj)) { pr_warn("BTF is required, but is missing or corrupted.\n"); return err; } @@ -2346,7 +2353,7 @@ static int bpf_object__finalize_btf(struct bpf_object *obj) btf_ext__free(obj->btf_ext); obj->btf_ext = NULL; - if (bpf_object__is_btf_mandatory(obj)) { + if (libbpf_needs_btf(obj)) { pr_warn("BTF is required, but is missing or corrupted.\n"); return -ENOENT; } @@ -2410,7 +2417,7 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj) obj->btf_ext = NULL; } - if (bpf_object__is_btf_mandatory(obj)) + if (kernel_needs_btf(obj)) return err; } return 0;