From patchwork Tue Dec 8 23:53:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 11960043 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=unavailable 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 661FEC4361B for ; Tue, 8 Dec 2020 23:54:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2915323B19 for ; Tue, 8 Dec 2020 23:54:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730398AbgLHXyc convert rfc822-to-8bit (ORCPT ); Tue, 8 Dec 2020 18:54:32 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:49442 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730594AbgLHXy1 (ORCPT ); Tue, 8 Dec 2020 18:54:27 -0500 Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.16.0.43/8.16.0.43) with SMTP id 0B8NePAW012311 for ; Tue, 8 Dec 2020 15:53:46 -0800 Received: from mail.thefacebook.com ([163.114.132.120]) by m0089730.ppops.net with ESMTP id 35ac7qbu5g-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 08 Dec 2020 15:53:46 -0800 Received: from intmgw002.03.ash8.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:11d::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 8 Dec 2020 15:53:44 -0800 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 34DB62ECAF6B; Tue, 8 Dec 2020 15:53:34 -0800 (PST) From: Andrii Nakryiko To: , , , CC: , , Alan Maguire Subject: [PATCH v2 bpf-next] libbpf: support module BTF for BPF_TYPE_ID_TARGET CO-RE relocation Date: Tue, 8 Dec 2020 15:53:32 -0800 Message-ID: <20201208235332.354826-1-andrii@kernel.org> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.343,18.0.737 definitions=2020-12-08_17:2020-12-08,2020-12-08 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 clxscore=1015 bulkscore=0 lowpriorityscore=0 spamscore=0 impostorscore=0 mlxscore=0 adultscore=0 mlxlogscore=999 priorityscore=1501 suspectscore=8 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2012080150 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net When Clang emits ldimm64 instruction for BPF_TYPE_ID_TARGET CO-RE relocation, put module BTF FD, containing target type, into upper 32 bits of imm64. Because this FD is internal to libbpf, it's very cumbersome to test this in selftests. Manual testing was performed with debug log messages sprinkled across selftests and libbpf, confirming expected values are substituted. Better testing will be performed as part of the work adding module BTF types support to bpf_snprintf_btf() helpers. v1->v2: - fix crash on failing to resolve target spec (Alan). Cc: Alan Maguire Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 9be88a90a4aa..2fb9824bf9bf 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -4795,6 +4795,7 @@ static int load_module_btfs(struct bpf_object *obj) mod_btf = &obj->btf_modules[obj->btf_module_cnt++]; + btf__set_fd(btf, fd); mod_btf->btf = btf; mod_btf->id = id; mod_btf->fd = fd; @@ -5445,6 +5446,10 @@ struct bpf_core_relo_res __u32 orig_type_id; __u32 new_sz; __u32 new_type_id; + /* FD of the module BTF containing the target candidate, or 0 for + * vmlinux BTF + */ + int btf_obj_fd; }; /* Calculate original and target relocation values, given local and target @@ -5469,6 +5474,7 @@ static int bpf_core_calc_relo(const struct bpf_program *prog, res->fail_memsz_adjust = false; res->orig_sz = res->new_sz = 0; res->orig_type_id = res->new_type_id = 0; + res->btf_obj_fd = 0; if (core_relo_is_field_based(relo->kind)) { err = bpf_core_calc_field_relo(prog, relo, local_spec, @@ -5519,6 +5525,9 @@ static int bpf_core_calc_relo(const struct bpf_program *prog, } else if (core_relo_is_type_based(relo->kind)) { err = bpf_core_calc_type_relo(relo, local_spec, &res->orig_val); err = err ?: bpf_core_calc_type_relo(relo, targ_spec, &res->new_val); + if (!err && relo->kind == BPF_TYPE_ID_TARGET && + targ_spec && targ_spec->btf != prog->obj->btf_vmlinux) + res->btf_obj_fd = btf__fd(targ_spec->btf); } else if (core_relo_is_enumval_based(relo->kind)) { err = bpf_core_calc_enumval_relo(relo, local_spec, &res->orig_val); err = err ?: bpf_core_calc_enumval_relo(relo, targ_spec, &res->new_val); @@ -5725,10 +5734,14 @@ static int bpf_core_patch_insn(struct bpf_program *prog, } insn[0].imm = new_val; - insn[1].imm = 0; /* currently only 32-bit values are supported */ - pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %u\n", + /* btf_obj_fd is zero for all relos but BPF_TYPE_ID_TARGET + * with target type in the kernel module BTF + */ + insn[1].imm = res->btf_obj_fd; + pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %llu\n", prog->name, relo_idx, insn_idx, - (unsigned long long)imm, new_val); + (unsigned long long)imm, + ((unsigned long long)res->btf_obj_fd << 32) | new_val); break; } default: