From mboxrd@z Thu Jan 1 00:00:00 1970 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=-6.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=no 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 1CE72C433E1 for ; Tue, 18 Aug 2020 22:39:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA1DF20709 for ; Tue, 18 Aug 2020 22:39:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="mKHRqZKN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727011AbgHRWjj (ORCPT ); Tue, 18 Aug 2020 18:39:39 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:23074 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726957AbgHRWjh (ORCPT ); Tue, 18 Aug 2020 18:39:37 -0400 Received: from pps.filterd (m0109333.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 07IMGOU2002561 for ; Tue, 18 Aug 2020 15:39:37 -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=nma8tot9rRwTO5qxrDZMQrTsjCyz/EcBnR3sRhh1OZI=; b=mKHRqZKNRXEcRx1kvyOaJQQSQyOkAkbo4vzRzHDQh+WRQjxQREMEXbflzOiUsMFtELSy MipkptrLcsedHVj9PsOb2h88nNNi9PGCpA6Bjn5B6w1t9J9JRe3lHCfS01Ame16EbXiq k0zhmhdD405kExrA/KM1wxYN4eAwhR7H+pI= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 3304pawdrn-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 18 Aug 2020 15:39:37 -0700 Received: from intmgw003.08.frc2.facebook.com (2620:10d:c085:208::11) by mail.thefacebook.com (2620:10d:c085:11d::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 18 Aug 2020 15:39:36 -0700 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 57F322EC5EB9; Tue, 18 Aug 2020 15:39:28 -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 0/9] Add support for type-based and enum value-based CO-RE relocations Date: Tue, 18 Aug 2020 15:39:12 -0700 Message-ID: <20200818223921.2911963-1-andriin@fb.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-18_16:2020-08-18,2020-08-18 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 mlxscore=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 adultscore=0 spamscore=0 phishscore=0 priorityscore=1501 suspectscore=0 clxscore=1015 mlxlogscore=991 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008180160 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This patch set adds libbpf support to two new classes of CO-RE relocation= s: type-based (TYPE_EXISTS/TYPE_SIZE/TYPE_ID_LOCAL/TYPE_ID_TARGET) and enum value-vased (ENUMVAL_EXISTS/ENUMVAL_VALUE): - TYPE_EXISTS allows to detect presence in kernel BTF of a locally-reco= rded BTF type. Useful for feature detection (new functionality often comes= with new internal kernel types), as well as handling type renames and bigg= er refactorings. - TYPE_SIZE allows to get the real size (in bytes) of a specified kerne= l type. Useful for dumping internal structure as-is through perfbuf or ringbuf. - TYPE_ID_LOCAL/TYPE_ID_TARGET allow to capture BTF type ID of a BTF ty= pe in program's BTF or kernel BTF, respectively. These could be used for high-performance and space-efficient generic data dumping/logging by relying on small and cheap BTF type ID as a data layout descriptor, f= or post-processing on user-space side. - ENUMVAL_EXISTS can be used for detecting the presence of enumerator v= alue in kernel's enum type. Most direct application is to detect BPF helpe= r support in kernel. - ENUMVAL_VALUE allows to relocate real integer value of kernel enumera= tor value, which is subject to change (e.g., always a potential issue for internal, non-UAPI, kernel enums). I've indicated potential applications for these relocations, but relocati= ons themselves are generic and unassuming and are designed to work correctly = even in unintended applications. Furthermore, relocated values become constant= s, known to the verifier and could and would be used for dead branch code detection and elimination. This makes them ideal to do all sorts of featu= re detection and guarding functionality that's not available on some older (= but still supported by BPF program) kernels, while having to compile and main= tain one unified source code. As part of this patch set, one potential issue with ambiguous CO-RE relocations was solved (see patch #3). There are also some improvements t= o the way debug relocation logs are emitted, helping to get a high-level idea o= f what's going on for users that are willing to dive deeper into the intern= als of libbpf (or libbpf contributors, of course). Selftests are added for all the new features and relocation ambiguity iss= ue is excercised as well. LLVM patches adding these relocation in Clang: - __builtin_btf_type_id() ([0], [1], [2]); - __builtin_preserve_type_info(), __builtin_preserve_enum_value() ([3],= [4]). rfc -> v1: - I've rebased patches on top of series [5], there is a very minor conf= lict in bpf_core_read.h due to comment change. Series [5] would most probably go in first anyway. [0] https://reviews.llvm.org/D74572 [1] https://reviews.llvm.org/D74668 [2] https://reviews.llvm.org/D85174 [3] https://reviews.llvm.org/D83878 [4] https://reviews.llvm.org/D83242 [5] https://patchwork.ozlabs.org/project/netdev/list/?series=3D196308&s= tate=3D* Andrii Nakryiko (9): libbpf: improve error logging for mismatched BTF kind cases libbpf: clean up and improve CO-RE reloc logging libbpf: improve relocation ambiguity detection selftests/bpf: add test validating failure on ambiguous relocation value libbpf: implement type-based CO-RE relocations support selftests/bpf: test TYPE_EXISTS and TYPE_SIZE CO-RE relocations selftests/bpf: add CO-RE relo test for TYPE_ID_LOCAL/TYPE_ID_TARGET libbpf: implement enum value-based CO-RE relocations selftests/bpf: add tests for ENUMVAL_EXISTS/ENUMVAL_VALUE relocations tools/lib/bpf/bpf_core_read.h | 80 +- tools/lib/bpf/btf.c | 17 +- tools/lib/bpf/btf.h | 38 - tools/lib/bpf/libbpf.c | 754 ++++++++++++++---- tools/lib/bpf/libbpf_internal.h | 84 +- .../selftests/bpf/prog_tests/core_reloc.c | 328 +++++++- .../bpf/progs/btf__core_reloc_enumval.c | 3 + .../progs/btf__core_reloc_enumval___diff.c | 3 + .../btf__core_reloc_enumval___err_missing.c | 3 + .../btf__core_reloc_enumval___val3_missing.c | 3 + .../btf__core_reloc_size___err_ambiguous.c | 4 + .../bpf/progs/btf__core_reloc_type_based.c | 3 + ...btf__core_reloc_type_based___all_missing.c | 3 + .../btf__core_reloc_type_based___diff_sz.c | 3 + ...f__core_reloc_type_based___fn_wrong_args.c | 3 + .../btf__core_reloc_type_based___incompat.c | 3 + .../bpf/progs/btf__core_reloc_type_id.c | 3 + ...tf__core_reloc_type_id___missing_targets.c | 3 + .../selftests/bpf/progs/core_reloc_types.h | 352 +++++++- .../bpf/progs/test_core_reloc_enumval.c | 69 ++ .../bpf/progs/test_core_reloc_type_based.c | 107 +++ .../bpf/progs/test_core_reloc_type_id.c | 94 +++ 22 files changed, 1727 insertions(+), 233 deletions(-) create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_enu= mval.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_enu= mval___diff.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_enu= mval___err_missing.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_enu= mval___val3_missing.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_siz= e___err_ambiguous.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_typ= e_based.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_typ= e_based___all_missing.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_typ= e_based___diff_sz.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_typ= e_based___fn_wrong_args.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_typ= e_based___incompat.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_typ= e_id.c create mode 100644 tools/testing/selftests/bpf/progs/btf__core_reloc_typ= e_id___missing_targets.c create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_enu= mval.c create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_typ= e_based.c create mode 100644 tools/testing/selftests/bpf/progs/test_core_reloc_typ= e_id.c --=20 2.24.1