From patchwork Fri Nov 13 08:38:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gary Lin X-Patchwork-Id: 1399633 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=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256 header.s=mimecast20200619 header.b=mmiyxN9F; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4CXX2Q6fZ0z9sTv for ; Fri, 13 Nov 2020 19:39:26 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726229AbgKMIjZ (ORCPT ); Fri, 13 Nov 2020 03:39:25 -0500 Received: from de-smtp-delivery-52.mimecast.com ([62.140.7.52]:60803 "EHLO de-smtp-delivery-52.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726149AbgKMIjZ (ORCPT ); Fri, 13 Nov 2020 03:39:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=mimecast20200619; t=1605256761; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=WWpbBqfKuGd2K6RnF+MTDL+1VI1DGMZ+u0+6hNJ8SHQ=; b=mmiyxN9Fs9lYk+aAuNyt5Ub/eyyCcR9DTr9Z+kTNPro+HbPPbWEalGyfww5zryUBRJS6u2 KW9zrQGywixz3DV8BwkK24iQyI8r6gnGwsTk0XbdoI+ABNe/v4/SRVt+79zd9gECuhfTSM cwS96lYOEyFSORCgNygygDQDEC9vHek= Received: from EUR04-VI1-obe.outbound.protection.outlook.com (mail-vi1eur04lp2055.outbound.protection.outlook.com [104.47.14.55]) (Using TLS) by relay.mimecast.com with ESMTP id de-mta-40-7_jcavCrO8-reddAroZBlg-1; Fri, 13 Nov 2020 09:39:19 +0100 X-MC-Unique: 7_jcavCrO8-reddAroZBlg-1 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=AEGtUM7++NxLXsMKy9/AQv+N6uXcvDBc+dXCcIPyzGHF3MphXVgHSkq1HigczS1ckrNeWnsmg7BGJ131BvoafhJy7DC7biHb3/X6LRLbSWKMdJ0TBaIG8pTMsR6uoSXQEI92diZ7VvVSpn4TABu5jsrL7sifAN+Q6OVNtZfy30AcqCKvQxIZhqOLPn/EOQVbQfrhZOrRYlW8A9OZdA31oQ6SDc6O8iBcJgqZn0ja4vLXj48ZBV7lDTiA+Ti2geGJSn5z+fHmXNeSQJQCC/tEhi+Kjfm4TALkrQSVMTUQWBMkJlZcVGQdzG4xXJytsldPDX/3sKZwayAKXJRbbA+Pjg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=xYaLrSBfx3edWy40um+qZanpNsDwYLxdh2LtlemenTU=; b=S7vPDs2JPlxm7/ZPpIOByp4XEiEL9EYgYMnLylpwqR2RlWsqT73kcOG8SMQSFH+nkh8F7EFdvUpbtExl8hDn37aH7YIxp502/O/j945KsKB/t2c3Efjn9jb5NSN5gOiDlYNpfOPpqY4KXR1H4HEJ/HmBaLR0YGx9Z8GNqfl49HHKAEy0rHj0JCXrE1hIm+5KQ4dBXybSFEBfkmHweH67vBeTKgINkc0qh7dlCzNmss0zQ8twsNugTlLNAfmDt751tV/7663WJV6plFi4+TnO5TRtS/KvDfLN7RxFIfP2oSR3JkK1Q1G6J8dn62PYoaeYXKmhTRDnlQqNtxWQKJG75A== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none Authentication-Results: kernel.org; dkim=none (message not signed) header.d=none;kernel.org; dmarc=none action=none header.from=suse.com; Received: from DB3PR0402MB3641.eurprd04.prod.outlook.com (2603:10a6:8:b::12) by DB7PR04MB5068.eurprd04.prod.outlook.com (2603:10a6:10:14::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3564.25; Fri, 13 Nov 2020 08:39:18 +0000 Received: from DB3PR0402MB3641.eurprd04.prod.outlook.com ([fe80::c84:f086:9b2e:2bf1]) by DB3PR0402MB3641.eurprd04.prod.outlook.com ([fe80::c84:f086:9b2e:2bf1%7]) with mapi id 15.20.3455.040; Fri, 13 Nov 2020 08:39:18 +0000 From: Gary Lin CC: Alexei Starovoitov , Daniel Borkmann , netdev@vger.kernel.org, bpf@vger.kernel.org, andreas.taschner@suse.com Subject: [PATCH RFC] bpf, x64: allow not-converged images when BPF_JIT_ALWAYS_ON is set Date: Fri, 13 Nov 2020 16:38:52 +0800 Message-ID: <20201113083852.22294-1-glin@suse.com> X-Mailer: git-send-email 2.28.0 X-Originating-IP: [60.251.47.115] X-ClientProxiedBy: AM9P192CA0010.EURP192.PROD.OUTLOOK.COM (2603:10a6:20b:21d::15) To DB3PR0402MB3641.eurprd04.prod.outlook.com (2603:10a6:8:b::12) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from GaryWorkstation.suse.cz (60.251.47.115) by AM9P192CA0010.EURP192.PROD.OUTLOOK.COM (2603:10a6:20b:21d::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3541.25 via Frontend Transport; Fri, 13 Nov 2020 08:39:16 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 53190378-9884-436c-ee8f-08d887af9bfb X-MS-TrafficTypeDiagnostic: DB7PR04MB5068: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: XhELy+ejeyGfpQ+4Cy5Umy3ctEgfJNCiUv8G9DdwdEYFf+e3+Dsh3GTjXW3v57CeI0YchnBbXuezmhNALawn67ZbYfDULCbulFIlp+80WdgXyQsXh3dOP4oA78fgaz+5o/17wgcPgtvJArhfYoNcT1EW2LZk5gF+ZWudwMvEh8dswA9wFQa/Ree0pckUWEXRhIlgz/HMqPzK3edqHLT/UXEqtN7YPo/H0Hot0n5eMsSFKPaigiVfIXa7Y4VBEwycKpDzwIYmo+PPmRdEY4pcsc+OGYAkjIfMQ8pk9lb9G6fMouMp6blBbM0O2VHPaxBKIjXVZ8mBvUdFrEvUxshZfqabn08ah0zmOy4gXGjLknFG1yIa63dBFaiPu1MP8xjC X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DB3PR0402MB3641.eurprd04.prod.outlook.com;PTR:;CAT:NONE;SFS:(346002)(376002)(136003)(39860400002)(396003)(366004)(8676002)(956004)(2616005)(8936002)(2906002)(1076003)(52116002)(6512007)(36756003)(83380400001)(86362001)(16526019)(66946007)(54906003)(6666004)(316002)(478600001)(109986005)(107886003)(26005)(4326008)(5660300002)(55236004)(6486002)(66476007)(66556008)(6506007)(186003)(266003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData: 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 X-OriginatorOrg: suse.com X-MS-Exchange-CrossTenant-Network-Message-Id: 53190378-9884-436c-ee8f-08d887af9bfb X-MS-Exchange-CrossTenant-AuthSource: DB3PR0402MB3641.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Nov 2020 08:39:18.2009 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: Rd6vgqVidWr5yXBts8k6IZ/nNOCn7Om9QolY9249KBpLw3S+yOfO1Wy3WVmbMx0q X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB7PR04MB5068 To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The x64 bpf jit expects the bpf images converge within the given passes. However there is a corner case: l0: ldh [4] l1: jeq #0x537d, l2, l40 l2: ld [0] l3: jeq #0xfa163e0d, l4, l40 l4: ldh [12] l5: ldx #0xe l6: jeq #0x86dd, l41, l7 l7: jeq #0x800, l8, l41 l8: ld [x+16] l9: ja 41 [... repeated ja 41 ] l40: ja 41 l41: ret #0 l42: ld #len l43: ret a The bpf program contains 32 "ja 41" and do_jit() only removes one "ja 41" right before "l41: ret #0" for offset==0 in each pass, so bpf_int_jit_compile() needs to run do_jit() at least 32 times to eliminate those JMP instructions. Since the current max number of passes is 20, the bpf program couldn't converge within 20 passes and got rejected when BPF_JIT_ALWAYS_ON is set even though it's legit as a classic socket filter. A not-converged image may be not optimal but at least the bpf instructions are translated into x64 machine code. Maybe we could just issue a warning instead so that the program is still loaded and the user is also notified. On the other hand, if the size convergence is mandatory, then it deserves a document to collect the corner cases so that the user could know the limitations and how to work around them. Signed-off-by: Gary Lin Reported-by: kernel test robot --- arch/x86/net/bpf_jit_comp.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 796506dcfc42..90814c2daaae 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1972,6 +1972,8 @@ struct x64_jit_data { struct jit_context ctx; }; +#define MAX_JIT_PASSES 20 + struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) { struct bpf_binary_header *header = NULL; @@ -2042,7 +2044,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) * may converge on the last pass. In such case do one more * pass to emit the final image. */ - for (pass = 0; pass < 20 || image; pass++) { + for (pass = 0; pass < MAX_JIT_PASSES || image; pass++) { proglen = do_jit(prog, addrs, image, oldproglen, &ctx); if (proglen <= 0) { out_image: @@ -2054,13 +2056,22 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) } if (image) { if (proglen != oldproglen) { +#ifdef CONFIG_BPF_JIT_ALWAYS_ON + pr_warn("bpf_jit: proglen=%d != oldproglen=%d pass=%d\n", + proglen, oldproglen, pass); +#else pr_err("bpf_jit: proglen=%d != oldproglen=%d\n", proglen, oldproglen); goto out_image; +#endif } break; } +#ifdef CONFIG_BPF_JIT_ALWAYS_ON + if (proglen == oldproglen || pass >= (MAX_JIT_PASSES - 1)) { +#else if (proglen == oldproglen) { +#endif /* * The number of entries in extable is the number of BPF_LDX * insns that access kernel memory via "pointer to BTF type".