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,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 32F16C433DF for ; Wed, 19 Aug 2020 05:29:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0BE21206DA for ; Wed, 19 Aug 2020 05:29:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="eLm+pGAi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726671AbgHSF32 (ORCPT ); Wed, 19 Aug 2020 01:29:28 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:50696 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726560AbgHSF3Y (ORCPT ); Wed, 19 Aug 2020 01:29:24 -0400 Received: from pps.filterd (m0109334.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 07J5TOkX011228 for ; Tue, 18 Aug 2020 22:29:24 -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=+vs54gea/gmsTyOx4BEJ97vL+Tnoif+hN6edKA0W7Yw=; b=eLm+pGAiVg1tsn60wwGUTnXya4eZiMoZ4DsO+3Ub00UW0g1Vcl5ebHh0pe6NdqZzxzDO Gcqk0Ca5FRuRKR61rwqdZczRqbHc/yPFwOUhdbR+xhOuC5mBMB5gSmNrlejlT8qjssse 6xIbdsb7enwZDRo9jrimt8EDfvsKhgk4tAE= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 3304p7xx8h-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 18 Aug 2020 22:29:24 -0700 Received: from intmgw001.03.ash8.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:21d::6) 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 22:28:56 -0700 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 43C342EC5C14; Tue, 18 Aug 2020 22:28:52 -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 v2 bpf-next 0/5] Add support for type-based and enum value-based CO-RE relocations Date: Tue, 18 Aug 2020 22:28:44 -0700 Message-ID: <20200819052849.336700-1-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=2020-08-19_03:2020-08-18,2020-08-19 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 suspectscore=0 adultscore=0 priorityscore=1501 malwarescore=0 mlxlogscore=825 clxscore=1015 spamscore=0 bulkscore=0 mlxscore=0 lowpriorityscore=0 phishscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008190046 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 for two new classes of CO-RE relocatio= ns: 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. Selftests are added for all the new features. Selftests utilizing new Cla= ng built-ins are designed such that they will compile with older Clangs and = will be skipped during test runs. So this shouldn't cause any build and test failures on systems with slightly outdated Clang compiler. LLVM patches adding these relocation in Clang: - __builtin_btf_type_id() ([0], [1], [2]); - __builtin_preserve_type_info(), __builtin_preserve_enum_value() ([3],= [4]). [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 v1->v2: - selftests detect built-in support and are skipped if not found (Alexe= i). Andrii Nakryiko (5): 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/libbpf.c | 376 ++++++++++++++++-- tools/lib/bpf/libbpf_internal.h | 6 + .../selftests/bpf/prog_tests/core_reloc.c | 349 ++++++++++++++-- .../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 + .../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 | 327 ++++++++++++++- .../bpf/progs/test_core_reloc_enumval.c | 73 ++++ .../bpf/progs/test_core_reloc_kernel.c | 2 + .../bpf/progs/test_core_reloc_type_based.c | 111 ++++++ .../bpf/progs/test_core_reloc_type_id.c | 107 +++++ 20 files changed, 1408 insertions(+), 56 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_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