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 X-Spam-Level: X-Spam-Status: No, score=-24.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 8EAF9C4320A for ; Mon, 16 Aug 2021 12:45:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6ECC163276 for ; Mon, 16 Aug 2021 12:45:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233560AbhHPMqF (ORCPT ); Mon, 16 Aug 2021 08:46:05 -0400 Received: from smtp-fw-80007.amazon.com ([99.78.197.218]:41263 "EHLO smtp-fw-80007.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229643AbhHPMqE (ORCPT ); Mon, 16 Aug 2021 08:46:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.co.jp; i=@amazon.co.jp; q=dns/txt; s=amazon201209; t=1629117934; x=1660653934; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=0iphdgblcid4/vc9+DuQqfmovdVVnpiynNfRgC73Im4=; b=eSWbbbdOyiVCCNYggx4EjaR0+8Z+KDNJcX++asWwX7bjRFe5ZClPnPAj Bnho8sRbcuRNj4J2JFPHuUko6/Vaoc38jYCaBeFZXf+nGXIrB764vdTDq od2+1gXiftSqK6h5rGfZIFn8W3a1EYZjwciy6wqmg994pD7vptJ8J0CZN U=; X-IronPort-AV: E=Sophos;i="5.84,324,1620691200"; d="scan'208";a="19476828" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO email-inbound-relay-2c-579b7f5b.us-west-2.amazon.com) ([10.25.36.210]) by smtp-border-fw-80007.pdx80.corp.amazon.com with ESMTP; 16 Aug 2021 12:45:33 +0000 Received: from EX13MTAUWB001.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan3.pdx.amazon.com [10.236.137.198]) by email-inbound-relay-2c-579b7f5b.us-west-2.amazon.com (Postfix) with ESMTPS id 76CBFA43FA; Mon, 16 Aug 2021 12:45:32 +0000 (UTC) Received: from EX13D04ANC001.ant.amazon.com (10.43.157.89) by EX13MTAUWB001.ant.amazon.com (10.43.161.207) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Mon, 16 Aug 2021 12:45:31 +0000 Received: from 88665a182662.ant.amazon.com (10.43.161.153) by EX13D04ANC001.ant.amazon.com (10.43.157.89) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Mon, 16 Aug 2021 12:45:26 +0000 From: Kuniyuki Iwashima To: CC: , , , , , , , , , , , , , , Subject: Re: [PATCH v5 bpf-next 3/4] selftest/bpf: Implement sample UNIX domain socket iterator program. Date: Mon, 16 Aug 2021 21:45:22 +0900 Message-ID: <20210816124522.38487-1-kuniyu@amazon.co.jp> X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.43.161.153] X-ClientProxiedBy: EX13D48UWB004.ant.amazon.com (10.43.163.74) To EX13D04ANC001.ant.amazon.com (10.43.157.89) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Yonghong Song Date: Sun, 15 Aug 2021 11:10:49 -0700 > On 8/13/21 5:21 PM, Kuniyuki Iwashima wrote: > > From: Andrii Nakryiko > > Date: Fri, 13 Aug 2021 16:25:53 -0700 > >> On Thu, Aug 12, 2021 at 9:46 AM Kuniyuki Iwashima wrote: > >>> > >>> The iterator can output almost the same result compared to /proc/net/unix. > >>> The header line is aligned, and the Inode column uses "%8lu" because "%5lu" > >>> can be easily overflown. > >>> > >>> # cat /sys/fs/bpf/unix > >>> Num RefCount Protocol Flags Type St Inode Path > >> > >> It's totally my OCD, but why the column name is not aligned with > >> values? I mean the "Inode" column. It's left aligned, but values > >> (numbers) are right-aligned? I'd fix that while applying, but I can't > >> apply due to selftests failures, so please take a look. > > > > Ah, honestly, I've felt something strange about the column... will fix it! > > > > > >> > >> > >>> ffff963c06689800: 00000002 00000000 00010000 0001 01 18697 private/defer > >>> ffff963c7c979c00: 00000002 00000000 00000000 0001 01 598245 @Hello@World@ > >>> > >>> # cat /proc/net/unix > >>> Num RefCount Protocol Flags Type St Inode Path > >>> ffff963c06689800: 00000002 00000000 00010000 0001 01 18697 private/defer > >>> ffff963c7c979c00: 00000002 00000000 00000000 0001 01 598245 @Hello@World@ > >>> > >>> Note that this prog requires the patch ([0]) for LLVM code gen. Thanks to > >>> Yonghong Song for analysing and fixing. > >>> > >>> [0] https://reviews.llvm.org/D107483 > >>> > >>> Signed-off-by: Kuniyuki Iwashima > >>> Acked-by: Yonghong Song > >>> --- > >> > >> This selftests breaks test_progs-no_alu32 ([0], the error log is super > >> long and can freeze browser; it looks like an infinite loop and BPF > >> verifier just keeps reporting it until it runs out of 1mln > >> instructions or something). Please check what's going on there, I > >> can't land it as it is right now. > >> > >> [0] https://github.com/kernel-patches/bpf/runs/3326071112?check_suite_focus=true#step:6:124288 > >> > >> > >>> tools/testing/selftests/bpf/README.rst | 38 +++++++++ > >>> .../selftests/bpf/prog_tests/bpf_iter.c | 16 ++++ > >>> tools/testing/selftests/bpf/progs/bpf_iter.h | 8 ++ > >>> .../selftests/bpf/progs/bpf_iter_unix.c | 77 +++++++++++++++++++ > >>> .../selftests/bpf/progs/bpf_tracing_net.h | 4 + > >>> 5 files changed, 143 insertions(+) > >>> create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_unix.c > >>> > >> > >> [...] > >> > >>> + /* The name of the abstract UNIX domain socket starts > >>> + * with '\0' and can contain '\0'. The null bytes > >>> + * should be escaped as done in unix_seq_show(). > >>> + */ > >>> + int i, len; > >>> + > >> > >> no_alu32 variant probably isn't happy about using int for this, it > >> probably does << 32, >> 32 dance and loses track of actual value in > >> the loop. You can try using u64 instead. > > > > Sorry, I missed the no_alu32 test. > > Changing int to __u64 fixed the error, thanks! > > Indeed for no_alu32, the index has << 32 and >> 32, which makes > verifier *equivalent* register tracking not effective, see below: > > 96: r1 = r8 > > 97: r1 <<= 32 > > 98: r2 = r1 > > 99: r2 >>= 32 > > 100: if r2 > 109 goto +19 > > 101: r1 s>>= 32 > > 102: if r1 s< 2 goto +17 > > 103: r9 = 1 > > 104: r8 <<= 32 > > 105: r8 >>= 32 > > Because these shifting, r1/r2/r8 equivalence cannot be > easily established, so verifier ends with conservative > r8 and cannot verify program successfully. > > Using __u64 for 'i' and 'len', the upper bound is directly > tested: > 98: if r8 > 109 goto +16 > > 99: if r8 < 2 goto +15 > and verifier is very happy with this. Thanks for explanation! I understand that the shift dance is to mimic the overflow of int because actually 64-bit register is allocated to 'i' and 32-bit operations cannot be used in no_alu32 test, so using __64 to remove the dance resolves it. > > > > > > >> > >>> + len = unix_sk->addr->len - sizeof(short); > >>> + > >>> + BPF_SEQ_PRINTF(seq, " @"); > >>> + > >>> + /* unix_mkname() tests this upper bound. */ > >>> + if (len < sizeof(struct sockaddr_un)) > >>> + for (i = 1; i < len; i++) > >> > >> if you move above if inside the loop to break out of the loop, does it > >> change how Clang generates code? > >> > >> for (i = 1; i < len i++) { > >> if (i >= sizeof(struct sockaddr_un)) > >> break; > >> BPF_SEQ_PRINTF(...); > >> } > > > > Yes, but there seems little defference. > > Which is preferable? > > > > ---8<--- > > before (for inside if) <- -> after (if inside loop) > > 96: 07 08 00 00 fe ff ff ff r8 += -2 | ; for (i = 1; i < len; i++) { > > ; if (len < sizeof(struct sockaddr_un)) | 97: bf 81 00 00 00 00 00 00 r1 = r8 > > 97: 25 08 10 00 6d 00 00 00 if r8 > 109 goto +16 | 98: 07 01 00 00 fc ff ff ff r1 += -4 > > ; for (i = 1; i < len; i++) | 99: 25 01 12 00 6b 00 00 00 if r1 > 107 goto +18 > > 98: a5 08 0f 00 02 00 00 00 if r8 < 2 goto +15 | 100: 07 08 00 00 fe ff ff ff r8 += -2 > > 99: b7 09 00 00 01 00 00 00 r9 = 1 | 101: b7 09 00 00 01 00 00 00 r9 = 1 > > 100: 05 00 16 00 00 00 00 00 goto +22 | 102: b7 06 00 00 02 00 00 00 r6 = 2 > > | 103: 05 00 17 00 00 00 00 00 goto +23 > > ... > > 111: 85 00 00 00 7e 00 00 00 call 126 | 113: b4 05 00 00 08 00 00 00 w5 = 8 > > ; for (i = 1; i < len; i++) | 114: 85 00 00 00 7e 00 00 00 call 126 > > 112: 07 09 00 00 01 00 00 00 r9 += 1 | ; for (i = 1; i < len; i++) { > > 113: ad 89 09 00 00 00 00 00 if r9 < r8 goto +9 | 115: 25 08 02 00 6d 00 00 00 if r8 > 109 goto +2 > > > 116: 07 09 00 00 01 00 00 00 r9 += 1 > > > ; for (i = 1; i < len; i++) { > > > 117: ad 89 09 00 00 00 00 00 if r9 < r8 goto +9 > > ---8<--- > > > > > >> > >> > >>> + BPF_SEQ_PRINTF(seq, "%c", > >>> + unix_sk->addr->name->sun_path[i] ?: > >>> + '@'); > >>> + } > >>> + } > >>> + > >>> + BPF_SEQ_PRINTF(seq, "\n"); > >>> + > >>> + return 0; > >>> +} > >>> diff --git a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h > >>> index 3af0998a0623..eef5646ddb19 100644 > >>> --- a/tools/testing/selftests/bpf/progs/bpf_tracing_net.h > >>> +++ b/tools/testing/selftests/bpf/progs/bpf_tracing_net.h > >>> @@ -5,6 +5,10 @@ > >>> #define AF_INET 2 > >>> #define AF_INET6 10 > >>> > >>> +#define __SO_ACCEPTCON (1 << 16) > >>> +#define UNIX_HASH_SIZE 256 > >>> +#define UNIX_ABSTRACT(unix_sk) (unix_sk->addr->hash < UNIX_HASH_SIZE) > >>> + > >>> #define SOL_TCP 6 > >>> #define TCP_CONGESTION 13 > >>> #define TCP_CA_NAME_MAX 16 > >>> -- > >>> 2.30.2 > >>>