From: Andrii Nakryiko andrii@kernel.org
mainline inclusion from mainline-5.11-rc1 commit fe62de310e2b563c0d303a09d06b020077fe86b4 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Support finding kernel targets in kernel modules when using bpf_program__set_attach_target() API. This brings it up to par with what libbpf supports when doing declarative SEC()-based target determination.
Some minor internal refactoring was needed to make sure vmlinux BTF can be loaded before bpf_object's load phase.
Signed-off-by: Andrii Nakryiko andrii@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/bpf/20201211215825.3646154-2-andrii@kernel.org (cherry picked from commit fe62de310e2b563c0d303a09d06b020077fe86b4) Signed-off-by: Wang Yufen wangyufen@huawei.com --- tools/lib/bpf/libbpf.c | 64 ++++++++++++++++++++++++++---------------- 1 file changed, 40 insertions(+), 24 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index fdf8441ec8a0..a0a1b7c99f2f 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -2519,7 +2519,7 @@ static int bpf_object__finalize_btf(struct bpf_object *obj) return 0; }
-static inline bool libbpf_prog_needs_vmlinux_btf(struct bpf_program *prog) +static bool prog_needs_vmlinux_btf(struct bpf_program *prog) { if (prog->type == BPF_PROG_TYPE_STRUCT_OPS || prog->type == BPF_PROG_TYPE_LSM || @@ -2535,37 +2535,43 @@ static inline bool libbpf_prog_needs_vmlinux_btf(struct bpf_program *prog) return false; }
-static int bpf_object__load_vmlinux_btf(struct bpf_object *obj) +static bool obj_needs_vmlinux_btf(const struct bpf_object *obj) { - bool need_vmlinux_btf = false; struct bpf_program *prog; - int i, err; + int i;
/* CO-RE relocations need kernel BTF */ if (obj->btf_ext && obj->btf_ext->core_relo_info.len) - need_vmlinux_btf = true; + return true;
/* Support for typed ksyms needs kernel BTF */ for (i = 0; i < obj->nr_extern; i++) { const struct extern_desc *ext;
ext = &obj->externs[i]; - if (ext->type == EXT_KSYM && ext->ksym.type_id) { - need_vmlinux_btf = true; - break; - } + if (ext->type == EXT_KSYM && ext->ksym.type_id) + return true; }
bpf_object__for_each_program(prog, obj) { if (!prog->load) continue; - if (libbpf_prog_needs_vmlinux_btf(prog)) { - need_vmlinux_btf = true; - break; - } + if (prog_needs_vmlinux_btf(prog)) + return true; }
- if (!need_vmlinux_btf) + return false; +} + +static int bpf_object__load_vmlinux_btf(struct bpf_object *obj, bool force) +{ + int err; + + /* btf_vmlinux could be loaded earlier */ + if (obj->btf_vmlinux) + return 0; + + if (!force && !obj_needs_vmlinux_btf(obj)) return 0;
obj->btf_vmlinux = libbpf_find_kernel_btf(); @@ -7533,7 +7539,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr) }
err = bpf_object__probe_loading(obj); - err = err ? : bpf_object__load_vmlinux_btf(obj); + err = err ? : bpf_object__load_vmlinux_btf(obj, false); err = err ? : bpf_object__resolve_externs(obj, obj->kconfig); err = err ? : bpf_object__sanitize_and_load_btf(obj); err = err ? : bpf_object__sanitize_maps(obj); @@ -10951,23 +10957,33 @@ int bpf_program__set_attach_target(struct bpf_program *prog, int attach_prog_fd, const char *attach_func_name) { - int btf_id; + int btf_obj_fd = 0, btf_id = 0, err;
if (!prog || attach_prog_fd < 0 || !attach_func_name) return -EINVAL;
- if (attach_prog_fd) + if (prog->obj->loaded) + return -EINVAL; + + if (attach_prog_fd) { btf_id = libbpf_find_prog_btf_id(attach_func_name, attach_prog_fd); - else - btf_id = libbpf_find_vmlinux_btf_id(attach_func_name, - prog->expected_attach_type); - - if (btf_id < 0) - return btf_id; + if (btf_id < 0) + return btf_id; + } else { + /* load btf_vmlinux, if not yet */ + err = bpf_object__load_vmlinux_btf(prog->obj, true); + if (err) + return err; + err = find_kernel_btf_id(prog->obj, attach_func_name, + prog->expected_attach_type, + &btf_obj_fd, &btf_id); + if (err) + return err; + }
prog->attach_btf_id = btf_id; - prog->attach_btf_obj_fd = 0; + prog->attach_btf_obj_fd = btf_obj_fd; prog->attach_prog_fd = attach_prog_fd; return 0; }