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 0AA29C05027 for ; Wed, 15 Feb 2023 03:03:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229454AbjBODDA (ORCPT ); Tue, 14 Feb 2023 22:03:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229506AbjBODC7 (ORCPT ); Tue, 14 Feb 2023 22:02:59 -0500 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 825BCBBBB for ; Tue, 14 Feb 2023 19:02:55 -0800 (PST) Received: by mail-pf1-x449.google.com with SMTP id x2-20020a056a000bc200b005a8ea29c7a6so1196022pfu.15 for ; Tue, 14 Feb 2023 19:02:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=vhvQUMjoFdnxKd1vKGkHiHtnmrXNJNR7pmkqsAc+VZA=; b=mxuyaXv9ndCjDF/QtupmeLvBQMItQIrveMbHhSZOYDC7JFSv4cqYyWOmj/GjAFVGNu djarZtu8xaoKZpHMls8UEg5Bh5wToD/j4ZDB/IriUGB80Bt+DM27j3g1JsOURBbdvBYB q0j3yHavQp2qU0maESpPSM5uSncRVXswxUvB4Tec6N7lC/23OobaZfqmKbQf56u5SJ0B RMsDVO30isQi8fvP0aTOPYwpEc0FBHrVSLFlnxRtzLsfiSpgdma618UGGec6QA/cHw1b k0x95HUeFZdwMcesTpEEbM/bprStDB+qxM0FsPN4Kjt86rmWJgIX8ImFzj5zm2tVU4po Gp/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=vhvQUMjoFdnxKd1vKGkHiHtnmrXNJNR7pmkqsAc+VZA=; b=KilcXNI8VtQWT2mx1fX9yCHx4nEXBDNeeGUDpLPV+V54wgYC45HKh22jg4aPMSy3md dhoffdfq+gf/Q6/8rWA8JtR/FI/qsh8ke1So3mjoaAmnRYHVpjknvcnpCkhiLy7k83U6 VmxcTtLevrlK8wvBoeqzB6+MvRbWpGTKNNmnRlC2/j3r09nc+0feaknpdgtuMpK2BAAH YNLQwMu/kHhcDYk6/kr5B2DdxStQdtGBLo2EiVAdXWPMwD6anp/qxGKykaF5TaSO/0dJ JueFnLV3TYVvI+eLPcVjhuEKzDH5JKyYO8OB863Yj9+SGW5K0V13fQnERU4Kk/ycvNp0 NXvg== X-Gm-Message-State: AO0yUKUpd55W7E3kneju4s3uyCSEtuQL3BPCzLpu1nEgTqV2pynvnpUM t99U4BnPOFhsWkHJ90LC87uSV7c= X-Google-Smtp-Source: AK7set+lgb3/ms+zvD0TVDWNUoClknXzolWi8DrLG/mlVpVSqOltH3K6qOYxY62fnzhpAD24nHl/nRw= X-Received: from sdf.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5935]) (user=sdf job=sendgmr) by 2002:a63:af59:0:b0:4fb:ee04:732a with SMTP id s25-20020a63af59000000b004fbee04732amr101573pgo.2.1676430174968; Tue, 14 Feb 2023 19:02:54 -0800 (PST) Date: Tue, 14 Feb 2023 19:02:53 -0800 In-Reply-To: <20230214235051.22938-1-alexei.starovoitov@gmail.com> Mime-Version: 1.0 References: <20230214235051.22938-1-alexei.starovoitov@gmail.com> Message-ID: Subject: Re: [PATCH bpf-next] selftests/bpf: Fix map_kptr test. From: Stanislav Fomichev To: Alexei Starovoitov Cc: davem@davemloft.net, daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org, memxor@gmail.com, netdev@vger.kernel.org, bpf@vger.kernel.org, kernel-team@fb.com Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 02/14, Alexei Starovoitov wrote: > From: Alexei Starovoitov > The compiler is optimizing out majority of unref_ptr read/writes, so the > test > wasn't testing much. For example, one could delete '__kptr' tag from > 'struct prog_test_ref_kfunc __kptr *unref_ptr;' and the test would > still "pass". > Convert it to volatile stores. Confirmed by comparing bpf asm > before/after. > Fixes: 2cbc469a6fc3 ("selftests/bpf: Add C tests for kptr") > Signed-off-by: Alexei Starovoitov Acked-by: Stanislav Fomichev > --- > tools/testing/selftests/bpf/progs/map_kptr.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > diff --git a/tools/testing/selftests/bpf/progs/map_kptr.c > b/tools/testing/selftests/bpf/progs/map_kptr.c > index eb8217803493..228ec45365a8 100644 > --- a/tools/testing/selftests/bpf/progs/map_kptr.c > +++ b/tools/testing/selftests/bpf/progs/map_kptr.c > @@ -62,21 +62,23 @@ extern struct prog_test_ref_kfunc * > bpf_kfunc_call_test_kptr_get(struct prog_test_ref_kfunc **p, int a, int > b) __ksym; > extern void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) > __ksym; [..] > +#define WRITE_ONCE(x, val) ((*(volatile typeof(x) *) &(x)) = (val)) (thinking out loud) Maybe time for us to put these into some common headers in the selftests. progs/test_ksyms_btf_null_check.c READ_ONCE as well.. > + > static void test_kptr_unref(struct map_value *v) > { > struct prog_test_ref_kfunc *p; > p = v->unref_ptr; > /* store untrusted_ptr_or_null_ */ > - v->unref_ptr = p; > + WRITE_ONCE(v->unref_ptr, p); > if (!p) > return; > if (p->a + p->b > 100) > return; > /* store untrusted_ptr_ */ > - v->unref_ptr = p; > + WRITE_ONCE(v->unref_ptr, p); > /* store NULL */ > - v->unref_ptr = NULL; > + WRITE_ONCE(v->unref_ptr, NULL); > } > static void test_kptr_ref(struct map_value *v) > @@ -85,7 +87,7 @@ static void test_kptr_ref(struct map_value *v) > p = v->ref_ptr; > /* store ptr_or_null_ */ > - v->unref_ptr = p; > + WRITE_ONCE(v->unref_ptr, p); > if (!p) > return; > if (p->a + p->b > 100) > @@ -99,7 +101,7 @@ static void test_kptr_ref(struct map_value *v) > return; > } > /* store ptr_ */ > - v->unref_ptr = p; > + WRITE_ONCE(v->unref_ptr, p); > bpf_kfunc_call_test_release(p); > p = bpf_kfunc_call_test_acquire(&(unsigned long){0}); > -- > 2.30.2