From patchwork Wed May 22 18:55:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiong Wang X-Patchwork-Id: 1103540 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=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=netronome.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=netronome-com.20150623.gappssmtp.com header.i=@netronome-com.20150623.gappssmtp.com header.b="Mz7ysbNm"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 458MKh0LWVz9sBV for ; Thu, 23 May 2019 04:56:08 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729726AbfEVS4B (ORCPT ); Wed, 22 May 2019 14:56:01 -0400 Received: from mail-wm1-f65.google.com ([209.85.128.65]:36925 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729627AbfEVSz5 (ORCPT ); Wed, 22 May 2019 14:55:57 -0400 Received: by mail-wm1-f65.google.com with SMTP id 7so3294593wmo.2 for ; Wed, 22 May 2019 11:55:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netronome-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=DX8u14woMWB0/T1N/svKd1Gm9eJRtJGFELY8NQbCyRY=; b=Mz7ysbNmLaE5gXN/Po+j5Ryh+3M1HCEftgGzCvxwZKFPUdCHAk/lkQzfKqDf/m4R95 PGynSLOuCH3N/kiowCR6PVWvl08QXWvgQMVlYmmv8ZNeglq4QqDIkrMHCiK9v6bjBwlf JQCz0/vq6UvFk78DIHDJvPg4KovxNQZ8mzA6In2bjxe2NLJzix1hAUeTqY5hP71dLfEo 2acX/Cj/SYIJvKyPl67x0s1PqsdfxGNArNBl2xjs/F9K7Chm8Zm/eJGU28IZRXwgakY/ nZJ1K1y2gf7Z587FAkK5QLd+KvG10qCZVHgr8vAffv+Z6zruohEckDHXCg/Gk5HAHbYM pbiQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=DX8u14woMWB0/T1N/svKd1Gm9eJRtJGFELY8NQbCyRY=; b=aEGwEinWt39MpjgmGRD5hOeM/RCo7f0g0UyBnEdlBaDiuwrWDFEkXCgK27OWaBTLNB a3vcU8OyaLy4L9qshE+qzso+qzuoMpVxllJ4ofvrcrqPH+sk9tTOBKrwnE1MOSndvDuJ llNiCNSDjHWdKCcJTyS3e2m7LXMHE+R+QnV//1R2ON6bxkqIiWceAlZ3nF0sDa6Qlym1 j2rfA9jZBghm537R1oHD3kztOjDrpl4xBFE7KAzNjMC19iH7DSYE3DdOe2rD7gZijf3J 3qi9/kMAPp3kxyxt6Zwvmng5iH/uCfHknyh4fhAqnmzJhAbXS8oHcGSGKaL4rDdZfDDP QCjA== X-Gm-Message-State: APjAAAVUMZUJN1tKl5iSJIAeYAA81BzTsLwLI+OA5TgBVL3rPBMnGqxV eVtj7D5pirCzZI0GqU32AxI10Q== X-Google-Smtp-Source: APXvYqx+Q4YYoHPEBaixzN8UXhyR6bv0r+b41ChEEjMTzEYLzWFAvcxECeHrTyDklxvdJpTtj1qGmw== X-Received: by 2002:a1c:9d0f:: with SMTP id g15mr8580188wme.97.1558551354525; Wed, 22 May 2019 11:55:54 -0700 (PDT) Received: from cbtest28.netronome.com ([217.38.71.146]) by smtp.gmail.com with ESMTPSA id t12sm16328801wro.2.2019.05.22.11.55.53 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 22 May 2019 11:55:53 -0700 (PDT) From: Jiong Wang To: alexei.starovoitov@gmail.com, daniel@iogearbox.net Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, oss-drivers@netronome.com, davem@davemloft.net, paul.burton@mips.com, udknight@gmail.com, zlim.lnx@gmail.com, illusionist.neo@gmail.com, naveen.n.rao@linux.ibm.com, sandipan@linux.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, jakub.kicinski@netronome.com, Jiong Wang Subject: [PATCH v7 bpf-next 05/16] bpf: introduce new bpf prog load flags "BPF_F_TEST_RND_HI32" Date: Wed, 22 May 2019 19:55:01 +0100 Message-Id: <1558551312-17081-6-git-send-email-jiong.wang@netronome.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1558551312-17081-1-git-send-email-jiong.wang@netronome.com> References: <1558551312-17081-1-git-send-email-jiong.wang@netronome.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org x86_64 and AArch64 perhaps are two arches that running bpf testsuite frequently, however the zero extension insertion pass is not enabled for them because of their hardware support. It is critical to guarantee the pass correction as it is supposed to be enabled at default for a couple of other arches, for example PowerPC, SPARC, arm, NFP etc. Therefore, it would be very useful if there is a way to test this pass on for example x86_64. The test methodology employed by this set is "poisoning" useless bits. High 32-bit of a definition is randomized if it is identified as not used by any later insn. Such randomization is only enabled under testing mode which is gated by the new bpf prog load flags "BPF_F_TEST_RND_HI32". Suggested-by: Alexei Starovoitov Signed-off-by: Jiong Wang --- include/uapi/linux/bpf.h | 18 ++++++++++++++++++ kernel/bpf/syscall.c | 4 +++- tools/include/uapi/linux/bpf.h | 18 ++++++++++++++++++ 3 files changed, 39 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 63e0cf6..daac8df 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -260,6 +260,24 @@ enum bpf_attach_type { */ #define BPF_F_ANY_ALIGNMENT (1U << 1) +/* BPF_F_TEST_RND_HI32 is used in BPF_PROG_LOAD command for testing purpose. + * Verifier does sub-register def/use analysis and identifies instructions whose + * def only matters for low 32-bit, high 32-bit is never referenced later + * through implicit zero extension. Therefore verifier notifies JIT back-ends + * that it is safe to ignore clearing high 32-bit for these instructions. This + * saves some back-ends a lot of code-gen. However such optimization is not + * necessary on some arches, for example x86_64, arm64 etc, whose JIT back-ends + * hence hasn't used verifier's analysis result. But, we really want to have a + * way to be able to verify the correctness of the described optimization on + * x86_64 on which testsuites are frequently exercised. + * + * So, this flag is introduced. Once it is set, verifier will randomize high + * 32-bit for those instructions who has been identified as safe to ignore them. + * Then, if verifier is not doing correct analysis, such randomization will + * regress tests to expose bugs. + */ +#define BPF_F_TEST_RND_HI32 (1U << 2) + /* When BPF ldimm64's insn[0].src_reg != 0 then this can have * two extensions: * diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index cb5440b..3d546b6 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1604,7 +1604,9 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) if (CHECK_ATTR(BPF_PROG_LOAD)) return -EINVAL; - if (attr->prog_flags & ~(BPF_F_STRICT_ALIGNMENT | BPF_F_ANY_ALIGNMENT)) + if (attr->prog_flags & ~(BPF_F_STRICT_ALIGNMENT | + BPF_F_ANY_ALIGNMENT | + BPF_F_TEST_RND_HI32)) return -EINVAL; if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 63e0cf6..daac8df 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -260,6 +260,24 @@ enum bpf_attach_type { */ #define BPF_F_ANY_ALIGNMENT (1U << 1) +/* BPF_F_TEST_RND_HI32 is used in BPF_PROG_LOAD command for testing purpose. + * Verifier does sub-register def/use analysis and identifies instructions whose + * def only matters for low 32-bit, high 32-bit is never referenced later + * through implicit zero extension. Therefore verifier notifies JIT back-ends + * that it is safe to ignore clearing high 32-bit for these instructions. This + * saves some back-ends a lot of code-gen. However such optimization is not + * necessary on some arches, for example x86_64, arm64 etc, whose JIT back-ends + * hence hasn't used verifier's analysis result. But, we really want to have a + * way to be able to verify the correctness of the described optimization on + * x86_64 on which testsuites are frequently exercised. + * + * So, this flag is introduced. Once it is set, verifier will randomize high + * 32-bit for those instructions who has been identified as safe to ignore them. + * Then, if verifier is not doing correct analysis, such randomization will + * regress tests to expose bugs. + */ +#define BPF_F_TEST_RND_HI32 (1U << 2) + /* When BPF ldimm64's insn[0].src_reg != 0 then this can have * two extensions: *