From patchwork Tue Jun 30 18:49:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hao Luo X-Patchwork-Id: 208324 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=-17.6 required=3.0 tests=DKIMWL_WL_MED, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT, USER_IN_DEF_DKIM_WL 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 D4A68C433DF for ; Tue, 30 Jun 2020 18:49:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A9D2E2068F for ; Tue, 30 Jun 2020 18:49:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="gDKmgaxn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726956AbgF3St3 (ORCPT ); Tue, 30 Jun 2020 14:49:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726543AbgF3St1 (ORCPT ); Tue, 30 Jun 2020 14:49:27 -0400 Received: from mail-qt1-x849.google.com (mail-qt1-x849.google.com [IPv6:2607:f8b0:4864:20::849]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 10F5DC03E97A for ; Tue, 30 Jun 2020 11:49:27 -0700 (PDT) Received: by mail-qt1-x849.google.com with SMTP id c5so15072608qtv.20 for ; Tue, 30 Jun 2020 11:49:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=LEHppYXCQPcRgd0zlbLe7CmHbNbqX0AwBnt1nKT8kmo=; b=gDKmgaxn/Cl6wcc1lPhuw4d+qqZAEQfqpIWDlxkB2OP7eOtiDx3WCaV9AFMCtBGcEW 6y4r4V13gqh1xMTARtmFL7ye+2ccgbPwchESgvOexvYAy6hhtgrGLCKG6QC3Vkrev2y+ IcxsPM4HEFx4vUl3Trmszcq2jN0HtzaH7vyAMM+/hVR7gCA6JLkndlLF4fRw/mi2fYa/ rqJwYliZI3TiCxV3OBUl6aFdha/b4dwy17RorxyAwRczDrSXGLV+oykGuVWj1ZNTPbvv I1GjO7O7ckRnbMSSppCivAiy/2XvKnfWVijFknFlTXq65JbU2aUhnsfHnxvk6sQUTHLf fWoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=LEHppYXCQPcRgd0zlbLe7CmHbNbqX0AwBnt1nKT8kmo=; b=E9fQmcdzv34VHxvVm1iAnLm3VoIHUV773l101Be459dqGnGxzGU3NlkEBRDDzsQtnF eOgvg9NLky4o+1+9tNjRzYMzhNf5l01g/SBTuXGP51XhL9gmTBXoP172pZsJPbgT3ceJ qRt8aU+Od8vaaHAOuM9qK3oGEAMcTGCGkPiheBi/ckUob9u5N9P4XKxf7mXJ3gLpWhN/ OLPY0I20XT9CDwf9H/y1FQSKBFZYNVU2OH3/zo+h6EaJShaMq7fFz7hq39URvgqzcSkU X3pnc7Z+EPoKQt8A0G5kAF1Cyb6pf1V63Tdi3mk5kwhwoCCL+21ZEQfdX80ndrbIUOwu ZOGw== X-Gm-Message-State: AOAM533RvVcEU+r2ieUrQZk1Ss/s98+equtObUKFDpCohbcIjJQ5HhbR 5k4dfW9o5eRRobr4CBFQuDmQyrmICR8= X-Google-Smtp-Source: ABdhPJwRys7ufIj6Wc7BHqYbfXPqG7SI1+88BKjiZMcxuVaaHmLS3yYhRz/blmSR7Scygm3uV5jRzePkDzQ= X-Received: by 2002:ad4:4105:: with SMTP id i5mr11143826qvp.170.1593542965986; Tue, 30 Jun 2020 11:49:25 -0700 (PDT) Date: Tue, 30 Jun 2020 11:49:22 -0700 Message-Id: <20200630184922.455439-1-haoluo@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.27.0.212.ge8ba1cc988-goog Subject: [PATCH bpf-next] selftests/bpf: Switch test_vmlinux to use hrtimer_range_start_ns. From: Hao Luo To: netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, linux-kselftest@vger.kernel.org Cc: sdf@google.com, Shuah Khan , Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Hao Luo Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org The test_vmlinux test uses hrtimer_nanosleep as hook to test tracing programs. But it seems Clang may have done an aggressive optimization, causing fentry and kprobe to not hook on this function properly on a Clang build kernel. A possible fix is switching to use a more reliable function, e.g. the ones exported to kernel modules such as hrtimer_range_start_ns. After we switch to using hrtimer_range_start_ns, the test passes again even on a clang build kernel. Tested: In a clang build kernel, the test fail even when the flags {fentry, kprobe}_called are set unconditionally in handle__kprobe() and handle__fentry(), which implies the programs do not hook on hrtimer_nanosleep() properly. This could be because clang's code transformation is too aggressive. test_vmlinux:PASS:skel_open 0 nsec test_vmlinux:PASS:skel_attach 0 nsec test_vmlinux:PASS:tp 0 nsec test_vmlinux:PASS:raw_tp 0 nsec test_vmlinux:PASS:tp_btf 0 nsec test_vmlinux:FAIL:kprobe not called test_vmlinux:FAIL:fentry not called After we switch to hrtimer_range_start_ns, the test passes. test_vmlinux:PASS:skel_open 0 nsec test_vmlinux:PASS:skel_attach 0 nsec test_vmlinux:PASS:tp 0 nsec test_vmlinux:PASS:raw_tp 0 nsec test_vmlinux:PASS:tp_btf 0 nsec test_vmlinux:PASS:kprobe 0 nsec test_vmlinux:PASS:fentry 0 nsec Signed-off-by: Hao Luo --- tools/testing/selftests/bpf/progs/test_vmlinux.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/test_vmlinux.c b/tools/testing/selftests/bpf/progs/test_vmlinux.c index 5611b564d3b1..29fa09d6a6c6 100644 --- a/tools/testing/selftests/bpf/progs/test_vmlinux.c +++ b/tools/testing/selftests/bpf/progs/test_vmlinux.c @@ -63,20 +63,20 @@ int BPF_PROG(handle__tp_btf, struct pt_regs *regs, long id) return 0; } -SEC("kprobe/hrtimer_nanosleep") -int BPF_KPROBE(handle__kprobe, - ktime_t rqtp, enum hrtimer_mode mode, clockid_t clockid) +SEC("kprobe/hrtimer_start_range_ns") +int BPF_KPROBE(handle__kprobe, struct hrtimer *timer, ktime_t tim, u64 delta_ns, + const enum hrtimer_mode mode) { - if (rqtp == MY_TV_NSEC) + if (tim == MY_TV_NSEC) kprobe_called = true; return 0; } -SEC("fentry/hrtimer_nanosleep") -int BPF_PROG(handle__fentry, - ktime_t rqtp, enum hrtimer_mode mode, clockid_t clockid) +SEC("fentry/hrtimer_start_range_ns") +int BPF_PROG(handle__fentry, struct hrtimer *timer, ktime_t tim, u64 delta_ns, + const enum hrtimer_mode mode) { - if (rqtp == MY_TV_NSEC) + if (tim == MY_TV_NSEC) fentry_called = true; return 0; }