diff options
| author |   Andrii Nakryiko <andriin@fb.com> | 2020-06-23 21:38:05 -0700 |
|---|---|---|
| committer |   Daniel Borkmann <daniel@iogearbox.net> | 2020-06-24 16:08:17 +0200 |
| commit | 192b6638eea5d40c99964291671fc0371b858f6e (patch) | |
| tree | aed8438045c9eff287d4c183bd90f0ab59a76af2 /tools/lib/bpf | |
| parent | libbpf: Fix spelling mistake "kallasyms" -> "kallsyms" (diff) | |
| download | linux-dev-192b6638eea5d40c99964291671fc0371b858f6e.tar.xz linux-dev-192b6638eea5d40c99964291671fc0371b858f6e.zip | |
libbpf: Prevent loading vmlinux BTF twice
Prevent loading/parsing vmlinux BTF twice in some cases: for CO-RE relocations
and for BTF-aware hooks (tp_btf, fentry/fexit, etc).
Fixes: a6ed02cac690 ("libbpf: Load btf_vmlinux only once per object.")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200624043805.1794620-1-andriin@fb.com
Diffstat (limited to 'tools/lib/bpf')
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index deea27aadcef..6b4955d170ff 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -2504,22 +2504,31 @@ static inline bool libbpf_prog_needs_vmlinux_btf(struct bpf_program *prog) static int bpf_object__load_vmlinux_btf(struct bpf_object *obj) { + bool need_vmlinux_btf = false; struct bpf_program *prog; int err; + /* CO-RE relocations need kernel BTF */ + if (obj->btf_ext && obj->btf_ext->field_reloc_info.len) + need_vmlinux_btf = true; + bpf_object__for_each_program(prog, obj) { if (libbpf_prog_needs_vmlinux_btf(prog)) { - obj->btf_vmlinux = libbpf_find_kernel_btf(); - if (IS_ERR(obj->btf_vmlinux)) { - err = PTR_ERR(obj->btf_vmlinux); - pr_warn("Error loading vmlinux BTF: %d\n", err); - obj->btf_vmlinux = NULL; - return err; - } - return 0; + need_vmlinux_btf = true; + break; } } + if (!need_vmlinux_btf) + return 0; + + obj->btf_vmlinux = libbpf_find_kernel_btf(); + if (IS_ERR(obj->btf_vmlinux)) { + err = PTR_ERR(obj->btf_vmlinux); + pr_warn("Error loading vmlinux BTF: %d\n", err); + obj->btf_vmlinux = NULL; + return err; + } return 0; } @@ -4945,8 +4954,8 @@ bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path) if (targ_btf_path) targ_btf = btf__parse_elf(targ_btf_path, NULL); else - targ_btf = libbpf_find_kernel_btf(); - if (IS_ERR(targ_btf)) { + targ_btf = obj->btf_vmlinux; + if (IS_ERR_OR_NULL(targ_btf)) { pr_warn("failed to get target BTF: %ld\n", PTR_ERR(targ_btf)); return PTR_ERR(targ_btf); } @@ -4987,7 +4996,9 @@ bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path) } out: - btf__free(targ_btf); + /* obj->btf_vmlinux is freed at the end of object load phase */ + if (targ_btf != obj->btf_vmlinux) + btf__free(targ_btf); if (!IS_ERR_OR_NULL(cand_cache)) { hashmap__for_each_entry(cand_cache, entry, i) { bpf_core_free_cands(entry->value); |