From patchwork Tue Sep 29 02:05:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 11804819 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C2474139A for ; Tue, 29 Sep 2020 02:05:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A666C2078B for ; Tue, 29 Sep 2020 02:05:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="rX0tl8na" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727342AbgI2CFr (ORCPT ); Mon, 28 Sep 2020 22:05:47 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:34324 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727325AbgI2CFr (ORCPT ); Mon, 28 Sep 2020 22:05:47 -0400 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 08T25jT2024140 for ; Mon, 28 Sep 2020 19:05:45 -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=KNxveQPaHGG1pCEoyZRCMLeEvUZuqztPobe7iMtIl6Q=; b=rX0tl8naBpm7/bpWhrKQI6x1JLcr9ZmG4mGro6dEYA+j1K/3yCpnlU+cXTwjZuXXb2sG aL4sSNNESBK7XQlLYnAD/18JD1ex0jz4Pufhh26Kb+thy5kSKY0YUJF9yG4buEbLkkVo XhhRxCcti/WyOJzbjoxzg0vUAUxjUd3DjoY= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 33t3cpajy7-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 28 Sep 2020 19:05:45 -0700 Received: from intmgw001.03.ash8.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::f) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Mon, 28 Sep 2020 19:05:37 -0700 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 8F6B72EC773C; Mon, 28 Sep 2020 19:05:36 -0700 (PDT) From: Andrii Nakryiko To: , , , CC: , , Andrii Nakryiko , Arnaldo Carvalho de Melo Subject: [PATCH v3 bpf-next 0/3] libbpf: BTF writer APIs Date: Mon, 28 Sep 2020 19:05:29 -0700 Message-ID: <20200929020533.711288-1-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=2.50.10434:6.0.235,18.0.687 definitions=2020-09-29_01:2020-09-28,2020-09-29 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0 malwarescore=0 clxscore=1015 impostorscore=0 mlxlogscore=343 suspectscore=8 priorityscore=1501 lowpriorityscore=0 spamscore=0 adultscore=0 mlxscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009290019 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org This patch set introduces a new set of BTF APIs to libbpf that allow to conveniently produce BTF types and strings. These APIs will allow libbpf to do more intrusive modifications of program's BTF (by rewriting it, at least as of right now), which is necessary for the upcoming libbpf static linking. But they are complete and generic, so can be adopted by anyone who has a need to produce BTF type information. One such example outside of libbpf is pahole, which was actually converted to these APIs (locally, pending landing of these changes in libbpf) completely and shows reduction in amount of custom pahole code necessary and brings nice savings in memory usage (about 370MB reduction at peak for my kernel configuration) and even BTF deduplication times (one second reduction, 23.7s -> 22.7s). Memory savings are due to avoiding pahole's own copy of "uncompressed" raw BTF data. Time reduction comes from faster string search and deduplication by relying on hashmap instead of BST used by pahole's own code. Consequently, these APIs are already tested on real-world complicated kernel BTF, but there is also pretty extensive selftest doing extra validations. Selftests in patch #3 add a set of generic ASSERT_{EQ,STREQ,ERR,OK} macros that are useful for writing shorter and less repretitive selftests. I decided to keep them local to that selftest for now, but if they prove to be useful in more contexts we should move them to test_progs.h. And few more (e.g., inequality tests) macros are probably necessary to have a more complete set. Cc: Arnaldo Carvalho de Melo v2->v3: - resending original patches #7-9 as patches #1-3 due to merge conflict; v1->v2: - fixed comments (John); - renamed btf__append_xxx() into btf__add_xxx() (Alexei); - added btf__find_str() in addition to btf__add_str(); - btf__new_empty() now sets kernel FD to -1 initially. Andrii Nakryiko (3): libbpf: add BTF writing APIs libbpf: add btf__str_by_offset() as a more generic variant of name_by_offset selftests/bpf: test BTF writing APIs tools/lib/bpf/btf.c | 796 +++++++++++++++++- tools/lib/bpf/btf.h | 39 + tools/lib/bpf/libbpf.map | 20 + .../selftests/bpf/prog_tests/btf_write.c | 278 ++++++ 4 files changed, 1128 insertions(+), 5 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/btf_write.c