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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 EFB87C33C9B for ; Wed, 8 Jan 2020 07:25:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD35720705 for ; Wed, 8 Jan 2020 07:25:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578468353; bh=e/+4eRBUv2HGdHAS6FsO6jt0I5tWdxxH90Oqc4HRE8s=; h=From:To:CC:Subject:Date:In-Reply-To:References:List-ID:From; b=zQUWZ9en5TFdqBLv1xT7Tbi+VCxrUbfVefMEDdZ+3LsnCZtsrKnRY2Ei8ZJEoYp6G EHqZvlRCBoWdx39eyXnO6tQEktI1HPduM4xIoAm5uOgMjQa9e1Srhe7xRQKtOeyTXU 0aGU6P43kKAmpqdb6YiwBN382WafSzIFoRvx0CRQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726793AbgAHHZx convert rfc822-to-8bit (ORCPT ); Wed, 8 Jan 2020 02:25:53 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:61470 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726731AbgAHHZw (ORCPT ); Wed, 8 Jan 2020 02:25:52 -0500 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 0087PKQT031129 for ; Tue, 7 Jan 2020 23:25:50 -0800 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 2xd5ah9cn7-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 07 Jan 2020 23:25:50 -0800 Received: from intmgw002.41.prn1.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 15.1.1779.2; Tue, 7 Jan 2020 23:25:49 -0800 Received: by devbig007.ftw2.facebook.com (Postfix, from userid 572438) id B6ECE760DB5; Tue, 7 Jan 2020 23:25:42 -0800 (PST) Smtp-Origin-Hostprefix: devbig From: Alexei Starovoitov Smtp-Origin-Hostname: devbig007.ftw2.facebook.com To: CC: , , , Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next 2/6] libbpf: Collect static vs global info about functions Date: Tue, 7 Jan 2020 23:25:34 -0800 Message-ID: <20200108072538.3359838-3-ast@kernel.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20200108072538.3359838-1-ast@kernel.org> References: <20200108072538.3359838-1-ast@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-01-08_01:2020-01-07,2020-01-08 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 mlxlogscore=999 impostorscore=0 suspectscore=1 priorityscore=1501 malwarescore=0 spamscore=0 lowpriorityscore=0 bulkscore=0 adultscore=0 clxscore=1015 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-2001080063 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Collect static vs global information about BPF functions from ELF file and improve BTF with this additional info if llvm is too old and doesn't emit it on its own. Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/libbpf.c | 115 +++++++++++++++++++++++++++++++++++++++-- 1 file changed, 111 insertions(+), 4 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index f72b3ed6c34b..2a4417d03ee2 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -294,6 +294,12 @@ struct extern_desc { static LIST_HEAD(bpf_objects_list); +struct func_desc { + int insn_idx; + int sec_idx; + enum btf_func_linkage linkage; +}; + struct bpf_object { char name[BPF_OBJ_NAME_LEN]; char license[64]; @@ -304,6 +310,8 @@ struct bpf_object { struct bpf_map *maps; size_t nr_maps; size_t maps_cap; + struct func_desc *funcs; + int nr_funcs; char *kconfig; struct extern_desc *externs; @@ -313,6 +321,7 @@ struct bpf_object { bool loaded; bool has_pseudo_calls; bool relaxed_core_relocs; + bool llvm_emits_func_linkage; /* * Information when doing elf related work. Only valid if fd @@ -526,10 +535,10 @@ bpf_object__init_prog_names(struct bpf_object *obj) continue; if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL) continue; - name = elf_strptr(obj->efile.elf, obj->efile.strtabidx, sym.st_name); + if (!name) { pr_warn("failed to get sym name string for prog %s\n", prog->section_name); @@ -2232,6 +2241,34 @@ static int cmp_externs(const void *_a, const void *_b) return strcmp(a->name, b->name); } +static int bpf_object__record_func_info(struct bpf_object *obj, GElf_Sym *sym) +{ + int bind = GELF_ST_BIND(sym->st_info); + bool static_func = bind == STB_LOCAL; + struct func_desc *f; + + /* + * Cannot check obj->caps.btf_func_linkage during elf open phase. + * Otherwise could have skipped collection of this info. + */ + + f = obj->funcs; + f = reallocarray(f, obj->nr_funcs + 1, sizeof(*f)); + if (!f) + return -ENOMEM; + obj->funcs = f; + f = &f[obj->nr_funcs]; + memset(f, 0, sizeof(*f)); + obj->nr_funcs++; + + f->insn_idx = sym->st_value / 8; + f->linkage = static_func ? BTF_FUNC_STATIC : BTF_FUNC_GLOBAL; + f->sec_idx = sym->st_shndx; + pr_debug("Func at insn %d sec %d linkage %d\n", + f->insn_idx, f->sec_idx, f->linkage); + return 0; +} + static int bpf_object__collect_externs(struct bpf_object *obj) { const struct btf_type *t; @@ -2258,6 +2295,12 @@ static int bpf_object__collect_externs(struct bpf_object *obj) if (!gelf_getsym(obj->efile.symbols, i, &sym)) return -LIBBPF_ERRNO__FORMAT; + if (GELF_ST_TYPE(sym.st_info) == STT_FUNC) { + int err = bpf_object__record_func_info(obj, &sym); + + if (err) + return err; + } if (!sym_is_extern(&sym)) continue; ext_name = elf_strptr(obj->efile.elf, obj->efile.strtabidx, @@ -3145,9 +3188,62 @@ check_btf_ext_reloc_err(struct bpf_program *prog, int err, return 0; } +static int btf_ext_improve_func_info(struct bpf_object *obj, + struct bpf_program *prog, + __u32 sec_idx) +{ + struct bpf_func_info_min *info; + struct btf_type *t; + struct func_desc *f; + const char *name; + int i, j; + + if (!obj->caps.btf_func_linkage || obj->llvm_emits_func_linkage) + /* + * If kernel doesn't understand func linkage or llvm emits + * it already into BTF then don't try to improve BTF based on + * ELF info. + */ + return 0; + + info = prog->func_info; + for (i = 0; i < prog->func_info_cnt; i++) { + for (j = 0; j < obj->nr_funcs; j++) { + f = &obj->funcs[j]; + if (f->insn_idx != info->insn_off || + f->sec_idx != sec_idx) + continue; + t = (void *)btf__type_by_id(obj->btf, info->type_id); + if (!t) + return -EINVAL; + name = btf__name_by_offset(obj->btf, t->name_off); + if (!name) + return -EINVAL; + pr_debug("Func '%s' at insn %d btf_id %d linkage in BTF %d in ELF %d\n", + name, info->insn_off, info->type_id, + BTF_INFO_VLEN(t->info), f->linkage); + if (BTF_INFO_VLEN(t->info) == f->linkage) { + if (BTF_INFO_VLEN(t->info)) { + /* llvm emits func linkage. Don't touch BTF */ + obj->llvm_emits_func_linkage = true; + return 0; + } + } else { + /* improve BTF with static vs global */ + t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, + f->linkage); + } + break; + } + info = ((void *)info) + prog->func_info_rec_size; + } + return 0; +} + static int bpf_program_reloc_btf_ext(struct bpf_program *prog, struct bpf_object *obj, - const char *section_name, __u32 insn_offset) + const char *section_name, __u32 insn_offset, + __u32 sec_idx) { int err; @@ -3168,6 +3264,15 @@ bpf_program_reloc_btf_ext(struct bpf_program *prog, struct bpf_object *obj, "bpf_func_info"); prog->func_info_rec_size = btf_ext__func_info_rec_size(obj->btf_ext); + if (!insn_offset) { + /* + * improve BTF_KIND_FUNC when func_info is allocated + * first time. Don't touch it during relocation. + */ + err = btf_ext_improve_func_info(obj, prog, sec_idx); + if (err) + return err; + } } if (!insn_offset || prog->line_info) { @@ -4308,7 +4413,8 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj, if (obj->btf_ext) { err = bpf_program_reloc_btf_ext(prog, obj, text->section_name, - prog->insns_cnt); + prog->insns_cnt, + text->idx); if (err) return err; } @@ -4336,7 +4442,8 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj) if (obj->btf_ext) { err = bpf_program_reloc_btf_ext(prog, obj, - prog->section_name, 0); + prog->section_name, 0, + prog->idx); if (err) return err; } -- 2.23.0