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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94589C43217 for ; Tue, 18 Oct 2022 03:57:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229784AbiJRD5E convert rfc822-to-8bit (ORCPT ); Mon, 17 Oct 2022 23:57:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229886AbiJRD5D (ORCPT ); Mon, 17 Oct 2022 23:57:03 -0400 Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72DEB8769C for ; Mon, 17 Oct 2022 20:57:00 -0700 (PDT) Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.17.1.5/8.17.1.5) with ESMTP id 29HNe4V5005799 for ; Mon, 17 Oct 2022 20:56:59 -0700 Received: from mail.thefacebook.com ([163.114.132.120]) by m0089730.ppops.net (PPS) with ESMTPS id 3k92jvjxvq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 17 Oct 2022 20:56:59 -0700 Received: from twshared25017.14.frc2.facebook.com (2620:10d:c085:108::4) 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 15.1.2375.31; Mon, 17 Oct 2022 20:56:58 -0700 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id 54C7820472015; Mon, 17 Oct 2022 20:56:50 -0700 (PDT) From: Andrii Nakryiko To: , , CC: , Subject: [PATCH bpf-next 1/3] libbpf: clean up and refactor BTF fixup step Date: Mon, 17 Oct 2022 20:56:44 -0700 Message-ID: <20221018035646.1294873-2-andrii@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221018035646.1294873-1-andrii@kernel.org> References: <20221018035646.1294873-1-andrii@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-ORIG-GUID: IDVuQTs9PQg8MQhc2LJitE_gEOai0VPE X-Proofpoint-GUID: IDVuQTs9PQg8MQhc2LJitE_gEOai0VPE X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-10-17_13,2022-10-17_02,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Refactor libbpf's BTF fixup step during BPF object open phase. The only functional change is that we now ignore BTF_VAR_GLOBAL_EXTERN variables during fix up, not just BTF_VAR_STATIC ones, which shouldn't cause any change in behavior as there shouldn't be any extern variable in data sections for valid BPF object anyways. Otherwise it's just collapsing two functions that have no reason to be separate, and switching find_elf_var_offset() helper to return entire symbol pointer, not just its offset. This will be used by next patch to get ELF symbol visibility. While refactoring, also "normalize" debug messages inside btf_fixup_datasec() to follow general libbpf style and print out data section name consistently, where it's available. Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 95 ++++++++++++++++++------------------------ 1 file changed, 41 insertions(+), 54 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 8c3f236c86e4..a25eb8fe7bf2 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -1461,15 +1461,12 @@ static int find_elf_sec_sz(const struct bpf_object *obj, const char *name, __u32 return -ENOENT; } -static int find_elf_var_offset(const struct bpf_object *obj, const char *name, __u32 *off) +static Elf64_Sym *find_elf_var_sym(const struct bpf_object *obj, const char *name) { Elf_Data *symbols = obj->efile.symbols; const char *sname; size_t si; - if (!name || !off) - return -EINVAL; - for (si = 0; si < symbols->d_size / sizeof(Elf64_Sym); si++) { Elf64_Sym *sym = elf_sym_by_idx(obj, si); @@ -1483,15 +1480,13 @@ static int find_elf_var_offset(const struct bpf_object *obj, const char *name, _ sname = elf_sym_str(obj, sym->st_name); if (!sname) { pr_warn("failed to get sym name string for var %s\n", name); - return -EIO; - } - if (strcmp(name, sname) == 0) { - *off = sym->st_value; - return 0; + return ERR_PTR(-EIO); } + if (strcmp(name, sname) == 0) + return sym; } - return -ENOENT; + return ERR_PTR(-ENOENT); } static struct bpf_map *bpf_object__add_map(struct bpf_object *obj) @@ -2850,57 +2845,62 @@ static int compare_vsi_off(const void *_a, const void *_b) static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf, struct btf_type *t) { - __u32 size = 0, off = 0, i, vars = btf_vlen(t); - const char *name = btf__name_by_offset(btf, t->name_off); - const struct btf_type *t_var; + __u32 size = 0, i, vars = btf_vlen(t); + const char *sec_name = btf__name_by_offset(btf, t->name_off); struct btf_var_secinfo *vsi; - const struct btf_var *var; - int ret; + int err; - if (!name) { + if (!sec_name) { pr_debug("No name found in string section for DATASEC kind.\n"); return -ENOENT; } - /* .extern datasec size and var offsets were set correctly during - * extern collection step, so just skip straight to sorting variables + /* extern-backing datasecs (.ksyms, .kconfig) have their size and + * variable offsets set at the previous step, so we skip any fixups + * for such sections */ if (t->size) goto sort_vars; - ret = find_elf_sec_sz(obj, name, &size); - if (ret || !size) { - pr_debug("Invalid size for section %s: %u bytes\n", name, size); + err = find_elf_sec_sz(obj, sec_name, &size); + if (err || !size) { + pr_debug("sec '%s': invalid size %u bytes\n", sec_name, size); return -ENOENT; } t->size = size; for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) { + const struct btf_type *t_var; + struct btf_var *var; + const char *var_name; + Elf64_Sym *sym; + t_var = btf__type_by_id(btf, vsi->type); if (!t_var || !btf_is_var(t_var)) { - pr_debug("Non-VAR type seen in section %s\n", name); + pr_debug("sec '%s': unexpected non-VAR type found\n", sec_name); return -EINVAL; } var = btf_var(t_var); - if (var->linkage == BTF_VAR_STATIC) + if (var->linkage == BTF_VAR_STATIC || var->linkage == BTF_VAR_GLOBAL_EXTERN) continue; - name = btf__name_by_offset(btf, t_var->name_off); - if (!name) { - pr_debug("No name found in string section for VAR kind\n"); + var_name = btf__name_by_offset(btf, t_var->name_off); + if (!var_name) { + pr_debug("sec '%s': failed to find name of DATASEC's member #%d\n", + sec_name, i); return -ENOENT; } - ret = find_elf_var_offset(obj, name, &off); - if (ret) { - pr_debug("No offset found in symbol table for VAR %s\n", - name); + sym = find_elf_var_sym(obj, var_name); + if (IS_ERR(sym)) { + pr_debug("sec '%s': failed to find ELF symbol for VAR '%s'\n", + sec_name, var_name); return -ENOENT; } - vsi->offset = off; + vsi->offset = sym->st_value; } sort_vars: @@ -2908,13 +2908,16 @@ static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf, return 0; } -static int btf_finalize_data(struct bpf_object *obj, struct btf *btf) +static int bpf_object_fixup_btf(struct bpf_object *obj) { - int err = 0; - __u32 i, n = btf__type_cnt(btf); + int i, n, err = 0; + if (!obj->btf) + return 0; + + n = btf__type_cnt(obj->btf); for (i = 1; i < n; i++) { - struct btf_type *t = btf_type_by_id(btf, i); + struct btf_type *t = btf_type_by_id(obj->btf, i); /* Loader needs to fix up some of the things compiler * couldn't get its hands on while emitting BTF. This @@ -2922,28 +2925,12 @@ static int btf_finalize_data(struct bpf_object *obj, struct btf *btf) * the info from the ELF itself for this purpose. */ if (btf_is_datasec(t)) { - err = btf_fixup_datasec(obj, btf, t); + err = btf_fixup_datasec(obj, obj->btf, t); if (err) - break; + return err; } } - return libbpf_err(err); -} - -static int bpf_object__finalize_btf(struct bpf_object *obj) -{ - int err; - - if (!obj->btf) - return 0; - - err = btf_finalize_data(obj, obj->btf); - if (err) { - pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err); - return err; - } - return 0; } @@ -7233,7 +7220,7 @@ static struct bpf_object *bpf_object_open(const char *path, const void *obj_buf, err = err ? : bpf_object__check_endianness(obj); err = err ? : bpf_object__elf_collect(obj); err = err ? : bpf_object__collect_externs(obj); - err = err ? : bpf_object__finalize_btf(obj); + err = err ? : bpf_object_fixup_btf(obj); err = err ? : bpf_object__init_maps(obj, opts); err = err ? : bpf_object_init_progs(obj, opts); err = err ? : bpf_object__collect_relos(obj); -- 2.30.2