From patchwork Wed Jun 24 04:38:05 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 1315837 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=fb.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=fb.com header.i=@fb.com header.a=rsa-sha256 header.s=facebook header.b=d29wAui7; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49s9Pz43Dyz9sSJ for ; Wed, 24 Jun 2020 14:38:31 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728681AbgFXEia (ORCPT ); Wed, 24 Jun 2020 00:38:30 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:32422 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727862AbgFXEi3 (ORCPT ); Wed, 24 Jun 2020 00:38:29 -0400 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 05O4W75k024000 for ; Tue, 23 Jun 2020 21:38:29 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=3AzvELCBJnKMvHSgbHT4AqvyHP0fR8lFsSr95PwDW/E=; b=d29wAui7nBOsbUZPN6AhPeek5wX0PrbcNngxukk8TivshPfD6QtSd7zE7kLGHd53+Xvm TTUr0GXxcKlQLNBEX8XBtscaNXP0BNg/8fJ2Dm7bkraHaC5JALKxtO0foasGgVB8wlKR Vqqur57+/YSH8J5dlWFnvq89mvXS41mXHa4= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 31ux1bgcsm-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 23 Jun 2020 21:38:29 -0700 Received: from intmgw001.03.ash8.facebook.com (2620:10d:c085:108::8) by mail.thefacebook.com (2620:10d:c085:21d::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 23 Jun 2020 21:38:28 -0700 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 2B6C92EC3938; Tue, 23 Jun 2020 21:38:24 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Andrii Nakryiko Smtp-Origin-Hostname: devbig012.ftw2.facebook.com To: , , , CC: , , Andrii Nakryiko Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next] libbpf: prevent loading vmlinux BTF twice Date: Tue, 23 Jun 2020 21:38:05 -0700 Message-ID: <20200624043805.1794620-1-andriin@fb.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216, 18.0.687 definitions=2020-06-24_01:2020-06-23,2020-06-24 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 suspectscore=25 malwarescore=0 mlxscore=0 lowpriorityscore=0 cotscore=-2147483648 mlxlogscore=999 phishscore=0 adultscore=0 impostorscore=0 spamscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006240033 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Prevent loading/parsing vmlinux BTF twice in some cases: for CO-RE relocations and for BTF-aware hooks (tp_btf, fentry/fexit, etc). Fixes: a6ed02cac690 ("libbpf: Load btf_vmlinux only once per object.") Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 18461deb1b19..1e77bbfe6c63 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -2504,22 +2504,31 @@ static inline bool libbpf_prog_needs_vmlinux_btf(struct bpf_program *prog) static int bpf_object__load_vmlinux_btf(struct bpf_object *obj) { + bool need_vmlinux_btf = false; struct bpf_program *prog; int err; + /* CO-RE relocations need kernel BTF */ + if (obj->btf_ext && obj->btf_ext->field_reloc_info.len) + need_vmlinux_btf = true; + bpf_object__for_each_program(prog, obj) { if (libbpf_prog_needs_vmlinux_btf(prog)) { - obj->btf_vmlinux = libbpf_find_kernel_btf(); - if (IS_ERR(obj->btf_vmlinux)) { - err = PTR_ERR(obj->btf_vmlinux); - pr_warn("Error loading vmlinux BTF: %d\n", err); - obj->btf_vmlinux = NULL; - return err; - } - return 0; + need_vmlinux_btf = true; + break; } } + if (!need_vmlinux_btf) + return 0; + + obj->btf_vmlinux = libbpf_find_kernel_btf(); + if (IS_ERR(obj->btf_vmlinux)) { + err = PTR_ERR(obj->btf_vmlinux); + pr_warn("Error loading vmlinux BTF: %d\n", err); + obj->btf_vmlinux = NULL; + return err; + } return 0; } @@ -4945,8 +4954,8 @@ bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path) if (targ_btf_path) targ_btf = btf__parse_elf(targ_btf_path, NULL); else - targ_btf = libbpf_find_kernel_btf(); - if (IS_ERR(targ_btf)) { + targ_btf = obj->btf_vmlinux; + if (IS_ERR_OR_NULL(targ_btf)) { pr_warn("failed to get target BTF: %ld\n", PTR_ERR(targ_btf)); return PTR_ERR(targ_btf); } @@ -4987,7 +4996,9 @@ bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path) } out: - btf__free(targ_btf); + /* obj->btf_vmlinux is freed at the end of object load phase */ + if (targ_btf != obj->btf_vmlinux) + btf__free(targ_btf); if (!IS_ERR_OR_NULL(cand_cache)) { hashmap__for_each_entry(cand_cache, entry, i) { bpf_core_free_cands(entry->value);