From patchwork Mon Nov 7 09:20:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yang Jihong X-Patchwork-Id: 13034182 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 8A37BC4321E for ; Mon, 7 Nov 2022 09:24:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231791AbiKGJX5 (ORCPT ); Mon, 7 Nov 2022 04:23:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231521AbiKGJXw (ORCPT ); Mon, 7 Nov 2022 04:23:52 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2D76E9588; Mon, 7 Nov 2022 01:23:52 -0800 (PST) Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4N5QlN1MxdzRp5Z; Mon, 7 Nov 2022 17:23:44 +0800 (CST) Received: from kwepemm600003.china.huawei.com (7.193.23.202) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 7 Nov 2022 17:23:48 +0800 Received: from ubuntu1804.huawei.com (10.67.174.61) by kwepemm600003.china.huawei.com (7.193.23.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 7 Nov 2022 17:23:47 +0800 From: Yang Jihong To: , , , , , , , , , , , , , , , , , , , , , , , , , , , CC: Subject: [PATCH bpf v2 3/5] libbpf: Skip adjust mem size for load pointer in 32-bit arch in CO_RE Date: Mon, 7 Nov 2022 17:20:30 +0800 Message-ID: <20221107092032.178235-4-yangjihong1@huawei.com> X-Mailer: git-send-email 2.30.GIT In-Reply-To: <20221107092032.178235-1-yangjihong1@huawei.com> References: <20221107092032.178235-1-yangjihong1@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.174.61] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm600003.china.huawei.com (7.193.23.202) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org bpf_core_patch_insn modifies load's mem size from 8 bytes to 4 bytes. As a result, the bpf check fails, we need to skip adjust mem size to fit the verifier. Signed-off-by: Yang Jihong --- tools/lib/bpf/libbpf.c | 34 +++++++++++++++++++++++++++++----- 1 file changed, 29 insertions(+), 5 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 184ce1684dcd..e1c21b631a0b 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -5634,6 +5634,28 @@ static int bpf_core_resolve_relo(struct bpf_program *prog, targ_res); } +static bool +bpf_core_patch_insn_skip(const struct btf *local_btf, const struct bpf_insn *insn, + const struct bpf_core_relo_res *res) +{ + __u8 class; + const struct btf_type *orig_t; + + class = BPF_CLASS(insn->code); + orig_t = btf_type_by_id(local_btf, res->orig_type_id); + + /* + * verifier has to see a load of a pointer as a 8-byte load, + * CO_RE should not screws up access, bpf_core_patch_insn modifies + * load's mem size from 8 bytes to 4 bytes in 32-bit arch, + * so we skip adjust mem size. + */ + if (class == BPF_LDX && btf_is_ptr(orig_t)) + return true; + + return false; +} + static int bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path) { @@ -5730,11 +5752,13 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path) goto out; } - err = bpf_core_patch_insn(prog->name, insn, insn_idx, rec, i, &targ_res); - if (err) { - pr_warn("prog '%s': relo #%d: failed to patch insn #%u: %d\n", - prog->name, i, insn_idx, err); - goto out; + if (!bpf_core_patch_insn_skip(obj->btf, insn, &targ_res)) { + err = bpf_core_patch_insn(prog->name, insn, insn_idx, rec, i, &targ_res); + if (err) { + pr_warn("prog '%s': relo #%d: failed to patch insn #%u: %d\n", + prog->name, i, insn_idx, err); + goto out; + } } } }