From patchwork Wed Sep 30 00:20:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 1373998 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=fb.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=fb.com header.i=@fb.com header.a=rsa-sha256 header.s=facebook header.b=RUjrkByY; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4C1H2t3w3Tz9sSC for ; Wed, 30 Sep 2020 10:20:22 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728931AbgI3AUV (ORCPT ); Tue, 29 Sep 2020 20:20:21 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:35772 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728192AbgI3AUV (ORCPT ); Tue, 29 Sep 2020 20:20:21 -0400 Received: from pps.filterd (m0109334.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 08U089mc006472 for ; Tue, 29 Sep 2020 17:20:21 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=h3BnLxZrQ4XlvvyA1YZ1bz1YPKF17/KsDORShehfmng=; b=RUjrkByYoOI/Ktis+Vrr3pZ0Sxh9GTrGDyuJHWmQ+MKFROC2bgd9ieer/aVO2ArNz8pe O1mNXAk9PJEOZU8ybnv7StXcn+eoqcnye41u7Otz8A2wr2lWINiZMe4xESfGuqRFqxri Ad8K8eeE4M2+0hd+Yl3//aab7HzAG5ik00k= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 33v1ndccf3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 29 Sep 2020 17:20:20 -0700 Received: from intmgw002.08.frc2.facebook.com (2620:10d:c085:208::11) by mail.thefacebook.com (2620:10d:c085:11d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 29 Sep 2020 17:20:20 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 0E51162E56EB; Tue, 29 Sep 2020 17:20:13 -0700 (PDT) From: Song Liu To: , CC: , , , , , Song Liu Subject: [PATCH v2 bpf-next] bpf: fix raw_tp test run in preempt kernel Date: Tue, 29 Sep 2020 17:20:10 -0700 Message-ID: <20200930002011.521337-1-songliubraving@fb.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-09-29_14:2020-09-29,2020-09-29 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 spamscore=0 mlxlogscore=739 clxscore=1015 priorityscore=1501 bulkscore=0 adultscore=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 phishscore=0 mlxscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009290205 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In preempt kernel, BPF_PROG_TEST_RUN on raw_tp triggers: [ 35.874974] BUG: using smp_processor_id() in preemptible [00000000] code: new_name/87 [ 35.893983] caller is bpf_prog_test_run_raw_tp+0xd4/0x1b0 [ 35.900124] CPU: 1 PID: 87 Comm: new_name Not tainted 5.9.0-rc6-g615bd02bf #1 [ 35.907358] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 35.916941] Call Trace: [ 35.919660] dump_stack+0x77/0x9b [ 35.923273] check_preemption_disabled+0xb4/0xc0 [ 35.928376] bpf_prog_test_run_raw_tp+0xd4/0x1b0 [ 35.933872] ? selinux_bpf+0xd/0x70 [ 35.937532] __do_sys_bpf+0x6bb/0x21e0 [ 35.941570] ? find_held_lock+0x2d/0x90 [ 35.945687] ? vfs_write+0x150/0x220 [ 35.949586] do_syscall_64+0x2d/0x40 [ 35.953443] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fix this by calling migrate_disable() before smp_processor_id(). Fixes: 1b4d60ec162f ("bpf: Enable BPF_PROG_TEST_RUN for raw_tracepoint") Reported-by: Alexei Starovoitov Signed-off-by: Song Liu --- Changes v1 => v2: 1. Keep rcu_read_lock/unlock() in original places. (Alexei) 2. Use get_cpu() instead of smp_processor_id(). (Alexei) --- net/bpf/test_run.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index fde5db93507c4..c1c30a9f76f34 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -252,9 +252,7 @@ __bpf_prog_test_run_raw_tp(void *data) struct bpf_raw_tp_test_run_info *info = data; rcu_read_lock(); - migrate_disable(); info->retval = BPF_PROG_RUN(info->prog, info->ctx); - migrate_enable(); rcu_read_unlock(); } @@ -266,6 +264,7 @@ int bpf_prog_test_run_raw_tp(struct bpf_prog *prog, __u32 ctx_size_in = kattr->test.ctx_size_in; struct bpf_raw_tp_test_run_info info; int cpu = kattr->test.cpu, err = 0; + int current_cpu; /* doesn't support data_in/out, ctx_out, duration, or repeat */ if (kattr->test.data_in || kattr->test.data_out || @@ -293,27 +292,25 @@ int bpf_prog_test_run_raw_tp(struct bpf_prog *prog, info.prog = prog; + current_cpu = get_cpu(); if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 || - cpu == smp_processor_id()) { + cpu == current_cpu) { __bpf_prog_test_run_raw_tp(&info); - } else { + } else if (cpu >= nr_cpu_ids || !cpu_online(cpu)) { /* smp_call_function_single() also checks cpu_online() * after csd_lock(). However, since cpu is from user * space, let's do an extra quick check to filter out * invalid value before smp_call_function_single(). */ - if (cpu >= nr_cpu_ids || !cpu_online(cpu)) { err = -ENXIO; - goto out; - } - + } else { err = smp_call_function_single(cpu, __bpf_prog_test_run_raw_tp, &info, 1); - if (err) - goto out; } + put_cpu(); - if (copy_to_user(&uattr->test.retval, &info.retval, sizeof(u32))) + if (!err && + copy_to_user(&uattr->test.retval, &info.retval, sizeof(u32))) err = -EFAULT; out: