From patchwork Wed May 29 13:20:00 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michal Rostecki X-Patchwork-Id: 1107146 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=opensuse.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 45DWWW04Lmz9sBb for ; Wed, 29 May 2019 23:19:03 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727111AbfE2NS6 (ORCPT ); Wed, 29 May 2019 09:18:58 -0400 Received: from mx2.suse.de ([195.135.220.15]:41218 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726863AbfE2NS6 (ORCPT ); Wed, 29 May 2019 09:18:58 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 27A7DAEB7; Wed, 29 May 2019 13:18:57 +0000 (UTC) From: Michal Rostecki Cc: Michal Rostecki , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , netdev@vger.kernel.org (open list:BPF (Safe dynamic programs and tools)), bpf@vger.kernel.org (open list:BPF (Safe dynamic programs and tools)), linux-kernel@vger.kernel.org (open list) Subject: [PATCH bpf v2] libbpf: Return btf_fd in libbpf__probe_raw_btf Date: Wed, 29 May 2019 15:20:00 +0200 Message-Id: <20190529132000.24942-1-mrostecki@opensuse.org> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Function load_sk_storage_btf expects that libbpf__probe_raw_btf is returning a BTF descriptor, but before this change it was returning an information about whether the probe was successful (0 or 1). load_sk_storage_btf was using that value as an argument of the close function, which was resulting in closing stdout and thus terminating the process which called that function. That bug was visible in bpftool. `bpftool feature` subcommand was always exiting too early (because of closed stdout) and it didn't display all requested probes. `bpftool -j feature` or `bpftool -p feature` were not returning a valid json object. v2: - Fix typo in the commit message. Fixes: d7c4b3980c18 ("libbpf: detect supported kernel BTF features and sanitize BTF") Signed-off-by: Michal Rostecki --- tools/lib/bpf/libbpf.c | 36 +++++++++++++++++++++-------------- tools/lib/bpf/libbpf_probes.c | 7 +------ 2 files changed, 23 insertions(+), 20 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 197b574406b3..bc2dca36bced 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -1645,15 +1645,19 @@ static int bpf_object__probe_btf_func(struct bpf_object *obj) /* FUNC x */ /* [3] */ BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2), }; - int res; + int btf_fd; + int ret; - res = libbpf__probe_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs)); - if (res < 0) - return res; - if (res > 0) + btf_fd = libbpf__probe_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs)); + if (btf_fd < 0) + ret = 0; + else { + ret = 1; obj->caps.btf_func = 1; - return 0; + } + close(btf_fd); + return ret; } static int bpf_object__probe_btf_datasec(struct bpf_object *obj) @@ -1670,15 +1674,19 @@ static int bpf_object__probe_btf_datasec(struct bpf_object *obj) BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4), BTF_VAR_SECINFO_ENC(2, 0, 4), }; - int res; + int btf_fd; + int ret; - res = libbpf__probe_raw_btf((char *)types, sizeof(types), - strs, sizeof(strs)); - if (res < 0) - return res; - if (res > 0) + btf_fd = libbpf__probe_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs)); + if (btf_fd < 0) + ret = 0; + else { + ret = 1; obj->caps.btf_datasec = 1; - return 0; + } + close(btf_fd); + return ret; } static int diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c index 5e2aa83f637a..2c2828345514 100644 --- a/tools/lib/bpf/libbpf_probes.c +++ b/tools/lib/bpf/libbpf_probes.c @@ -157,14 +157,9 @@ int libbpf__probe_raw_btf(const char *raw_types, size_t types_len, memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len); btf_fd = bpf_load_btf(raw_btf, btf_len, NULL, 0, false); - if (btf_fd < 0) { - free(raw_btf); - return 0; - } - close(btf_fd); free(raw_btf); - return 1; + return btf_fd; } static int load_sk_storage_btf(void)