Like maps and progs, add support to dump BTF objects by name ([0]). [0] Closes: https://github.com/libbpf/bpftool/issues/56 Signed-off-by: Hengqi Chen <hengqi.chen@xxxxxxxxx> --- tools/bpf/bpftool/btf.c | 92 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 91 insertions(+), 1 deletion(-) diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index 91fcb75babe3..cb8d78ff4081 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -547,6 +547,83 @@ static bool btf_is_kernel_module(__u32 btf_id) return btf_info.kernel_btf && strncmp(btf_name, "vmlinux", sizeof(btf_name)) != 0; } +static int btf_id_by_name(char *name, __u32 *btf_id) +{ + bool found = false; + __u32 id = 0; + int fd, err; + + while (true) { + struct bpf_btf_info info = {}; + __u32 len = sizeof(info); + char btf_name[64]; + + err = bpf_btf_get_next_id(id, &id); + if (err) { + if (errno == ENOENT) { + if (found) + err = 0; + else + p_err("no BTF object match name %s", name); + break; + } + + p_err("can't get next BTF object: %s%s", + strerror(errno), + errno == EINVAL ? " -- kernel too old?" : ""); + return -1; + } + + fd = bpf_btf_get_fd_by_id(id); + if (fd < 0) { + p_err("can't get BTF by id (%u): %s", + id, strerror(errno)); + return -1; + } + + err = bpf_btf_get_info_by_fd(fd, &info, &len); + if (err) { + p_err("can't get BTF info (%u): %s", + id, strerror(errno)); + goto err_close_fd; + } + + if (info.name_len) { + memset(&info, 0, sizeof(info)); + info.name_len = sizeof(btf_name); + info.name = ptr_to_u64(btf_name); + len = sizeof(info); + + err = bpf_btf_get_info_by_fd(fd, &info, &len); + if (err) { + p_err("can't get BTF info (%u): %s", + id, strerror(errno)); + goto err_close_fd; + } + } + + close(fd); + + if (strncmp(name, u64_to_ptr(info.name), BPF_OBJ_NAME_LEN)) + continue; + + if (found) { + p_err("multiple BTF object match name %s", name); + return -1; + } + + *btf_id = id; + found = true; + } + + return err; + +err_close_fd: + close(fd); + return err; +} + + static int do_dump(int argc, char **argv) { struct btf *btf = NULL, *base = NULL; @@ -637,6 +714,19 @@ static int do_dump(int argc, char **argv) *argv, strerror(errno)); goto done; } + NEXT_ARG(); + } else if (is_prefix(src, "name")) { + char *name = *argv; + + if (strlen(name) > BPF_OBJ_NAME_LEN - 1) { + p_err("can't parse name"); + return -1; + } + + err = btf_id_by_name(name, &btf_id); + if (err) + return -1; + NEXT_ARG(); } else { err = -1; @@ -1062,7 +1152,7 @@ static int do_help(int argc, char **argv) " %1$s %2$s dump BTF_SRC [format FORMAT]\n" " %1$s %2$s help\n" "\n" - " BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | value | kv | all}] | file FILE }\n" + " BTF_SRC := { id BTF_ID | name NAME | prog PROG | map MAP [{key | value | kv | all}] | file FILE }\n" " FORMAT := { raw | c }\n" " " HELP_SPEC_MAP "\n" " " HELP_SPEC_PROGRAM "\n" -- 2.34.1
