From patchwork Thu Nov 19 23:22:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 11919127 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A7CE8C63777 for ; Thu, 19 Nov 2020 23:22:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C933221FE for ; Thu, 19 Nov 2020 23:22:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726305AbgKSXWy convert rfc822-to-8bit (ORCPT ); Thu, 19 Nov 2020 18:22:54 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:22176 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725890AbgKSXWx (ORCPT ); Thu, 19 Nov 2020 18:22:53 -0500 Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0AJNKfHb027786 for ; Thu, 19 Nov 2020 15:22:53 -0800 Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 34wgckr7mm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 19 Nov 2020 15:22:53 -0800 Received: from intmgw003.03.ash8.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Thu, 19 Nov 2020 15:22:51 -0800 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 148FB2EC9B9C; Thu, 19 Nov 2020 15:22:50 -0800 (PST) From: Andrii Nakryiko To: , , , CC: , Subject: [PATCH bpf-next 2/6] libbpf: add internal helper to load BTF data by FD Date: Thu, 19 Nov 2020 15:22:40 -0800 Message-ID: <20201119232244.2776720-3-andrii@kernel.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20201119232244.2776720-1-andrii@kernel.org> References: <20201119232244.2776720-1-andrii@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-11-19_14:2020-11-19,2020-11-19 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 mlxscore=0 suspectscore=25 clxscore=1015 adultscore=0 spamscore=0 impostorscore=0 lowpriorityscore=0 bulkscore=0 priorityscore=1501 mlxlogscore=999 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011190160 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Add a btf_get_from_fd() helper, which constructs struct btf from in-kernel BTF data by FD. This is used for loading module BTFs. Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/btf.c | 61 +++++++++++++++++++-------------- tools/lib/bpf/libbpf_internal.h | 1 + 2 files changed, 36 insertions(+), 26 deletions(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 8ff46cd30ca1..541696d9aed6 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -1318,35 +1318,27 @@ const char *btf__name_by_offset(const struct btf *btf, __u32 offset) return btf__str_by_offset(btf, offset); } -int btf__get_from_id(__u32 id, struct btf **btf) +struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf) { - struct bpf_btf_info btf_info = { 0 }; + struct bpf_btf_info btf_info; __u32 len = sizeof(btf_info); __u32 last_size; - int btf_fd; + struct btf *btf; void *ptr; int err; - err = 0; - *btf = NULL; - btf_fd = bpf_btf_get_fd_by_id(id); - if (btf_fd < 0) - return 0; - /* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so * let's start with a sane default - 4KiB here - and resize it only if * bpf_obj_get_info_by_fd() needs a bigger buffer. */ - btf_info.btf_size = 4096; - last_size = btf_info.btf_size; + last_size = 4096; ptr = malloc(last_size); - if (!ptr) { - err = -ENOMEM; - goto exit_free; - } + if (!ptr) + return ERR_PTR(-ENOMEM); - memset(ptr, 0, last_size); + memset(&btf_info, 0, sizeof(btf_info)); btf_info.btf = ptr_to_u64(ptr); + btf_info.btf_size = last_size; err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len); if (!err && btf_info.btf_size > last_size) { @@ -1355,31 +1347,48 @@ int btf__get_from_id(__u32 id, struct btf **btf) last_size = btf_info.btf_size; temp_ptr = realloc(ptr, last_size); if (!temp_ptr) { - err = -ENOMEM; + btf = ERR_PTR(-ENOMEM); goto exit_free; } ptr = temp_ptr; - memset(ptr, 0, last_size); + + len = sizeof(btf_info); + memset(&btf_info, 0, sizeof(btf_info)); btf_info.btf = ptr_to_u64(ptr); + btf_info.btf_size = last_size; + err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len); } if (err || btf_info.btf_size > last_size) { - err = errno; + btf = err ? ERR_PTR(-errno) : ERR_PTR(-E2BIG); goto exit_free; } - *btf = btf__new((__u8 *)(long)btf_info.btf, btf_info.btf_size); - if (IS_ERR(*btf)) { - err = PTR_ERR(*btf); - *btf = NULL; - } + btf = btf_new(ptr, btf_info.btf_size, base_btf); exit_free: - close(btf_fd); free(ptr); + return btf; +} - return err; +int btf__get_from_id(__u32 id, struct btf **btf) +{ + struct btf *res; + int btf_fd; + + *btf = NULL; + btf_fd = bpf_btf_get_fd_by_id(id); + if (btf_fd < 0) + return 0; + + res = btf_get_from_fd(btf_fd, NULL); + close(btf_fd); + if (IS_ERR(res)) + return PTR_ERR(res); + + *btf = res; + return 0; } int btf__get_map_kv_tids(const struct btf *btf, const char *map_name, diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index d99bc847bf84..e569ae63808e 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -155,6 +155,7 @@ int bpf_object__section_size(const struct bpf_object *obj, const char *name, __u32 *size); int bpf_object__variable_offset(const struct bpf_object *obj, const char *name, __u32 *off); +struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf); struct btf_ext_info { /*