From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiko Carstens Subject: Re: "bpf: Improve the info.func_info and info.func_info_rec_size behavior" breaks strace self tests Date: Fri, 4 Jan 2019 10:25:24 +0100 Message-ID: <20190104092524.GC4396@osiris> References: <20190103114613.GB3957@osiris> <20190103191158.yu4cjkb3wd3zvpqk@kafai-mbp> <20190103224118.GA4491@osiris> <20190103235248.kxvhhwq4brcdxzps@kafai-mbp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit Cc: Eugene Syromyatnikov , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , Yonghong Song , Alexei Starovoitov , "Dmitry V. Levin" To: Martin Lau Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:51922 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726178AbfADJZe (ORCPT ); Fri, 4 Jan 2019 04:25:34 -0500 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id x049O87d013260 for ; Fri, 4 Jan 2019 04:25:33 -0500 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0a-001b2d01.pphosted.com with ESMTP id 2pt4j28tnc-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 04 Jan 2019 04:25:33 -0500 Received: from localhost by e06smtp04.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 4 Jan 2019 09:25:31 -0000 In-Reply-To: <20190103235248.kxvhhwq4brcdxzps@kafai-mbp> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Jan 03, 2019 at 11:52:51PM +0000, Martin Lau wrote: > On Thu, Jan 03, 2019 at 11:41:18PM +0100, Heiko Carstens wrote: > > On Thu, Jan 03, 2019 at 07:12:05PM +0000, Martin Lau wrote: > > > On Thu, Jan 03, 2019 at 12:46:13PM +0100, Heiko Carstens wrote: > > > > Hello, > > > > > > > > the kernel commit 7337224fc150 ("bpf: Improve the info.func_info and > > > > info.func_info_rec_size behavior") breaks one of strace's self tests: > > > > > > > > FAIL: bpf-obj_get_info_by_fd-prog-v.gen ... > I am running against linux-next. I don't see how root and non-root affect > thing here. I guess the test has been running without jit so far? Yes, it was disabled. Enabling jit and adding your memset fix leads to what you report with 2) below. > 1) root or not, if jit is enabled, > without the memset() fix in the bpf-obj_get_info_by_fd.c in my last email, > they all failed: > [root@arch-fb-vm1 tests]# ./bpf-obj_get_info_by_fd-prog-v.gen.test > BPF_OBJ_GET_INFO_BY_FD prog 2 failed: Bad address > bpf-obj_get_info_by_fd-prog-v.gen.test: skipped test: ../bpf-obj_get_info_by_fd-prog-v exited with code 77 > > Please fix this first. > > 2) After having the memset fix: > Root or not, for jited program, if I run > ./bpf-obj_get_info_by_fd-prog-v.gen.test, they failed. If I read the > init.sh correclty, it fails because there is a diff between the > ./bpf-obj_get_info_by_fd-prog-v stdout and the "strace -o log". I think > "strace -o log" only has the /* bytes 104..151 */ part if some bytes > are non-zero? > > Regardless, the test program "bpf-obj_get_info_by_fd.c" is telling > the kernel that the userspace "info" is in size 168 bytes. > The kernel then tells as much details as possible about > a bpf prog in "info". I don't see a ABI breakage here. > > I believe the test just happens to work so far because it has been running > without jit? > > If I run it with jit enabled: > -bpf(BPF_OBJ_GET_INFO_BY_FD, {info={bpf_fd=4, info_len=168, info={type=BPF_PROG_TYPE_SOCKET_FILTER, id=35, tag="\xda\xbf\x02\x07\xd1\x99\x24\x86", jited_prog_len=0 => 110, jited_prog_insns=NULL, xlated_prog_len=0 => 120, xlated_prog_insns=[], load_time=2476906063975, created_by_uid=0, nr_map_ids=0 => 1, map_ids=[], name="test_prog", ifindex=0, netns_dev=makedev(0, 0), netns_ino=0}}}, 16) = 0 > -bpf(BPF_OBJ_GET_INFO_BY_FD, {info={bpf_fd=4, info_len=168, info={type=BPF_PROG_TYPE_SOCKET_FILTER, id=35, tag="\xda\xbf\x02\x07\xd1\x99\x24\x86", jited_prog_len=0 => 110, jited_prog_insns=NULL, xlated_prog_len=0 => 120, xlated_prog_insns=[], load_time=2476906063975, created_by_uid=0, nr_map_ids=2 => 1, map_ids=[36], name="test_prog", ifindex=0, netns_dev=makedev(0, 0), netns_ino=0}}}, 16) = 0 > +bpf(BPF_OBJ_GET_INFO_BY_FD, {info={bpf_fd=4, info_len=168, info={type=BPF_PROG_TYPE_SOCKET_FILTER, id=35, tag="\xda\xbf\x02\x07\xd1\x99\x24\x86", jited_prog_len=0 => 110, jited_prog_insns=NULL, xlated_prog_len=0 => 120, xlated_prog_insns=[], load_time=2476906063975, created_by_uid=0, nr_map_ids=0 => 1, map_ids=[], name="test_prog", ifindex=0, netns_dev=makedev(0, 0), netns_ino=0, /* bytes 104..167 */ "\x01\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"}}}, 16) = 0 > +bpf(BPF_OBJ_GET_INFO_BY_FD, {info={bpf_fd=4, info_len=168, info={type=BPF_PROG_TYPE_SOCKET_FILTER, id=35, tag="\xda\xbf\x02\x07\xd1\x99\x24\x86", jited_prog_len=0 => 110, jited_prog_insns=NULL, xlated_prog_len=0 => 120, xlated_prog_insns=[], load_time=2476906063975, created_by_uid=0, nr_map_ids=2 => 1, map_ids=[36], name="test_prog", ifindex=0, netns_dev=makedev(0, 0), netns_ino=0, /* bytes 104..167 */ "\x01\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"}}}, 16) = 0 > > The diff comes in as early as byte 104-th which is the nr_jited_ksyms == 1. > > Please fix the test program. A protential fix is in bpf-obj_get_info_by_fd.c > to printf the non-zero "/* bytes 104..1xx */..." the same way as the > "strace -o log" does. Thanks a lot for looking into this! Eugene, Dmitry will you take care of fixing this?