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 094E2C433FE for ; Mon, 9 May 2022 01:29:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233965AbiEIBaq convert rfc822-to-8bit (ORCPT ); Sun, 8 May 2022 21:30:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235656AbiEIAqB (ORCPT ); Sun, 8 May 2022 20:46:01 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F1C16430 for ; Sun, 8 May 2022 17:42:09 -0700 (PDT) Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 248LewBJ004266 for ; Sun, 8 May 2022 17:42:08 -0700 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3fwpksdphq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Sun, 08 May 2022 17:42:08 -0700 Received: from twshared13579.04.prn5.facebook.com (2620:10d:c085:108::8) 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 15.1.2375.24; Sun, 8 May 2022 17:42:07 -0700 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id 5491319A4ACAD; Sun, 8 May 2022 17:41:55 -0700 (PDT) From: Andrii Nakryiko To: , , CC: , Subject: [PATCH bpf-next 3/9] libbpf: improve usability of field-based CO-RE helpers Date: Sun, 8 May 2022 17:41:42 -0700 Message-ID: <20220509004148.1801791-4-andrii@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220509004148.1801791-1-andrii@kernel.org> References: <20220509004148.1801791-1-andrii@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: 7tMNwIek2Y06qZK2m1s1AmoutH_k-0h_ X-Proofpoint-ORIG-GUID: 7tMNwIek2Y06qZK2m1s1AmoutH_k-0h_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-05-08_09,2022-05-06_01,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Allow to specify field reference in two ways: - if user has variable of necessary type, they can use variable-based reference (my_var.my_field or my_var_ptr->my_field). This was the only supported syntax up till now. - now, bpf_core_field_exists() and bpf_core_field_size() support also specifying field in a fashion similar to offsetof() macro, by specifying type of the containing struct/union separately and field name separately: bpf_core_field_exists(struct my_type, my_field). This forms is quite often more convenient in practice and it matches type-based CO-RE helpers that support specifying type by its name without requiring any variables. Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/bpf_core_read.h | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h index e4aa9996a550..5ad415f9051f 100644 --- a/tools/lib/bpf/bpf_core_read.h +++ b/tools/lib/bpf/bpf_core_read.h @@ -110,21 +110,38 @@ enum bpf_enum_value_kind { val; \ }) +#define ___bpf_field_ref1(field) (field) +#define ___bpf_field_ref2(type, field) (((typeof(type) *)0)->field) +#define ___bpf_field_ref(args...) \ + ___bpf_apply(___bpf_field_ref, ___bpf_narg(args))(args) + /* * Convenience macro to check that field actually exists in target kernel's. * Returns: * 1, if matching field is present in target kernel; * 0, if no matching field found. + * + * Supports two forms: + * - field reference through variable access: + * bpf_core_field_exists(p->my_field); + * - field reference through type and field names: + * bpf_core_field_exists(struct my_type, my_field). */ -#define bpf_core_field_exists(field) \ - __builtin_preserve_field_info(field, BPF_FIELD_EXISTS) +#define bpf_core_field_exists(field...) \ + __builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_EXISTS) /* * Convenience macro to get the byte size of a field. Works for integers, * struct/unions, pointers, arrays, and enums. + * + * Supports two forms: + * - field reference through variable access: + * bpf_core_field_size(p->my_field); + * - field reference through type and field names: + * bpf_core_field_size(struct my_type, my_field). */ -#define bpf_core_field_size(field) \ - __builtin_preserve_field_info(field, BPF_FIELD_BYTE_SIZE) +#define bpf_core_field_size(field...) \ + __builtin_preserve_field_info(___bpf_field_ref(field), BPF_FIELD_BYTE_SIZE) /* * Convenience macro to get BTF type ID of a specified type, using a local BTF -- 2.30.2