libbpf: Support attachment of BPF tracing programs to kernel modules
Teach libbpf to search for BTF types in kernel modules for tracing BPF programs. This allows attachment of raw_tp/fentry/fexit/fmod_ret/etc BPF program types to tracepoints and functions in kernel modules. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20201203204634.1325171-13-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko
Alexei Starovoitov
Родитель
6aef10a481
Коммит
91abb4a6d7
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@ -231,8 +231,11 @@ int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr)
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attr.prog_type = load_attr->prog_type;
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attr.expected_attach_type = load_attr->expected_attach_type;
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if (load_attr->attach_prog_fd)
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attr.attach_prog_fd = load_attr->attach_prog_fd;
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else
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attr.attach_btf_obj_fd = load_attr->attach_btf_obj_fd;
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attr.attach_btf_id = load_attr->attach_btf_id;
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attr.attach_prog_fd = load_attr->attach_prog_fd;
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attr.prog_ifindex = load_attr->prog_ifindex;
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attr.kern_version = load_attr->kern_version;
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@ -278,6 +278,7 @@ struct bpf_program {
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enum bpf_prog_type type;
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enum bpf_attach_type expected_attach_type;
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int prog_ifindex;
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__u32 attach_btf_obj_fd;
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__u32 attach_btf_id;
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__u32 attach_prog_fd;
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void *func_info;
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@ -408,6 +409,7 @@ struct module_btf {
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struct btf *btf;
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char *name;
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__u32 id;
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int fd;
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};
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struct bpf_object {
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@ -4766,8 +4768,7 @@ static int load_module_btfs(struct bpf_object *obj)
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if (err) {
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err = -errno;
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pr_warn("failed to get BTF object #%d info: %d\n", id, err);
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close(fd);
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return err;
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goto err_out;
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}
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/* ignore non-module BTFs */
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@ -4777,25 +4778,33 @@ static int load_module_btfs(struct bpf_object *obj)
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}
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btf = btf_get_from_fd(fd, obj->btf_vmlinux);
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close(fd);
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if (IS_ERR(btf)) {
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pr_warn("failed to load module [%s]'s BTF object #%d: %ld\n",
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name, id, PTR_ERR(btf));
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return PTR_ERR(btf);
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err = PTR_ERR(btf);
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goto err_out;
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}
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err = btf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap,
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sizeof(*obj->btf_modules), obj->btf_module_cnt + 1);
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if (err)
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return err;
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goto err_out;
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mod_btf = &obj->btf_modules[obj->btf_module_cnt++];
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mod_btf->btf = btf;
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mod_btf->id = id;
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mod_btf->fd = fd;
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mod_btf->name = strdup(name);
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if (!mod_btf->name)
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return -ENOMEM;
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if (!mod_btf->name) {
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err = -ENOMEM;
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goto err_out;
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}
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continue;
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err_out:
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close(fd);
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return err;
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}
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return 0;
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@ -6841,7 +6850,10 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
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load_attr.insn_cnt = insns_cnt;
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load_attr.license = license;
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load_attr.attach_btf_id = prog->attach_btf_id;
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load_attr.attach_prog_fd = prog->attach_prog_fd;
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if (prog->attach_prog_fd)
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load_attr.attach_prog_fd = prog->attach_prog_fd;
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else
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load_attr.attach_btf_obj_fd = prog->attach_btf_obj_fd;
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load_attr.attach_btf_id = prog->attach_btf_id;
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load_attr.kern_version = kern_version;
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load_attr.prog_ifindex = prog->prog_ifindex;
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@ -6937,11 +6949,11 @@ out:
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return ret;
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}
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static int libbpf_find_attach_btf_id(struct bpf_program *prog);
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static int libbpf_find_attach_btf_id(struct bpf_program *prog, int *btf_obj_fd, int *btf_type_id);
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int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
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{
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int err = 0, fd, i, btf_id;
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int err = 0, fd, i;
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if (prog->obj->loaded) {
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pr_warn("prog '%s': can't load after object was loaded\n", prog->name);
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@ -6951,10 +6963,14 @@ int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
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if ((prog->type == BPF_PROG_TYPE_TRACING ||
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prog->type == BPF_PROG_TYPE_LSM ||
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prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) {
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btf_id = libbpf_find_attach_btf_id(prog);
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if (btf_id <= 0)
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return btf_id;
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prog->attach_btf_id = btf_id;
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int btf_obj_fd = 0, btf_type_id = 0;
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err = libbpf_find_attach_btf_id(prog, &btf_obj_fd, &btf_type_id);
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if (err)
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return err;
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prog->attach_btf_obj_fd = btf_obj_fd;
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prog->attach_btf_id = btf_type_id;
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}
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if (prog->instances.nr < 0 || !prog->instances.fds) {
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@ -7467,6 +7483,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
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/* clean up module BTFs */
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for (i = 0; i < obj->btf_module_cnt; i++) {
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close(obj->btf_modules[i].fd);
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btf__free(obj->btf_modules[i].btf);
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free(obj->btf_modules[i].name);
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}
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@ -8821,8 +8838,8 @@ static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
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return btf__find_by_name_kind(btf, btf_type_name, kind);
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}
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static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name,
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enum bpf_attach_type attach_type)
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static inline int find_attach_btf_id(struct btf *btf, const char *name,
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enum bpf_attach_type attach_type)
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{
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int err;
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@ -8838,9 +8855,6 @@ static inline int __find_vmlinux_btf_id(struct btf *btf, const char *name,
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else
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err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
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if (err <= 0)
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pr_warn("%s is not found in vmlinux BTF\n", name);
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return err;
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}
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@ -8856,7 +8870,10 @@ int libbpf_find_vmlinux_btf_id(const char *name,
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return -EINVAL;
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}
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err = __find_vmlinux_btf_id(btf, name, attach_type);
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err = find_attach_btf_id(btf, name, attach_type);
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if (err <= 0)
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pr_warn("%s is not found in vmlinux BTF\n", name);
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btf__free(btf);
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return err;
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}
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@ -8894,11 +8911,49 @@ out:
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return err;
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}
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static int libbpf_find_attach_btf_id(struct bpf_program *prog)
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static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name,
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enum bpf_attach_type attach_type,
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int *btf_obj_fd, int *btf_type_id)
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{
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int ret, i;
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ret = find_attach_btf_id(obj->btf_vmlinux, attach_name, attach_type);
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if (ret > 0) {
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*btf_obj_fd = 0; /* vmlinux BTF */
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*btf_type_id = ret;
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return 0;
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}
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if (ret != -ENOENT)
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return ret;
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ret = load_module_btfs(obj);
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if (ret)
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return ret;
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for (i = 0; i < obj->btf_module_cnt; i++) {
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const struct module_btf *mod = &obj->btf_modules[i];
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ret = find_attach_btf_id(mod->btf, attach_name, attach_type);
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if (ret > 0) {
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*btf_obj_fd = mod->fd;
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*btf_type_id = ret;
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return 0;
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}
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if (ret == -ENOENT)
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continue;
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return ret;
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}
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return -ESRCH;
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}
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static int libbpf_find_attach_btf_id(struct bpf_program *prog, int *btf_obj_fd, int *btf_type_id)
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{
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enum bpf_attach_type attach_type = prog->expected_attach_type;
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__u32 attach_prog_fd = prog->attach_prog_fd;
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const char *name = prog->sec_name;
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const char *name = prog->sec_name, *attach_name;
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const struct bpf_sec_def *sec = NULL;
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int i, err;
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if (!name)
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@ -8909,17 +8964,37 @@ static int libbpf_find_attach_btf_id(struct bpf_program *prog)
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continue;
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if (strncmp(name, section_defs[i].sec, section_defs[i].len))
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continue;
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if (attach_prog_fd)
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err = libbpf_find_prog_btf_id(name + section_defs[i].len,
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attach_prog_fd);
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else
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err = __find_vmlinux_btf_id(prog->obj->btf_vmlinux,
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name + section_defs[i].len,
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attach_type);
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sec = §ion_defs[i];
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break;
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}
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if (!sec) {
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pr_warn("failed to identify BTF ID based on ELF section name '%s'\n", name);
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return -ESRCH;
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}
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attach_name = name + sec->len;
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/* BPF program's BTF ID */
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if (attach_prog_fd) {
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err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd);
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if (err < 0) {
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pr_warn("failed to find BPF program (FD %d) BTF ID for '%s': %d\n",
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attach_prog_fd, attach_name, err);
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return err;
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}
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*btf_obj_fd = 0;
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*btf_type_id = err;
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return 0;
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}
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/* kernel/module BTF ID */
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err = find_kernel_btf_id(prog->obj, attach_name, attach_type, btf_obj_fd, btf_type_id);
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if (err) {
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pr_warn("failed to find kernel BTF type ID of '%s': %d\n", attach_name, err);
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return err;
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}
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pr_warn("failed to identify btf_id based on ELF section name '%s'\n", name);
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return -ESRCH;
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return 0;
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}
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int libbpf_attach_type_by_name(const char *name,
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@ -10808,6 +10883,7 @@ int bpf_program__set_attach_target(struct bpf_program *prog,
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return btf_id;
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prog->attach_btf_id = btf_id;
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prog->attach_btf_obj_fd = 0;
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prog->attach_prog_fd = attach_prog_fd;
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return 0;
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}
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@ -160,6 +160,7 @@ struct bpf_prog_load_params {
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const char *license;
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__u32 kern_version;
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__u32 attach_prog_fd;
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__u32 attach_btf_obj_fd;
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__u32 attach_btf_id;
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__u32 prog_ifindex;
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__u32 prog_btf_fd;
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