From patchwork Fri May 24 11:35:15 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiong Wang X-Patchwork-Id: 1104843 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="UZ1Ng0cB"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 459PSs6MpLz9s3l for ; Fri, 24 May 2019 21:35:57 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391126AbfEXLfz (ORCPT ); Fri, 24 May 2019 07:35:55 -0400 Received: from mail-wm1-f68.google.com ([209.85.128.68]:52320 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390865AbfEXLfx (ORCPT ); Fri, 24 May 2019 07:35:53 -0400 Received: by mail-wm1-f68.google.com with SMTP id y3so9045850wmm.2 for ; Fri, 24 May 2019 04:35:52 -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=UZ1Ng0cB6tRBgt0MkN1f2QmfqIWsvAtoU5hE52bip+XYpMUPLgjEJp2mgh2a3uIUbY rrl6PXLC2MoYi66XS/sk1bRnkte8c5/o6lMLVeyEy3PXuf7VB0IVdle98c5vezLLVuYm gFOlbJzC98vEVR6q0+1p7MkrW3dktIoQ9MXNDVTwxc6RX4w2klw8pHjRzV852O2Ex4L6 Q5pVFYQG3+TapaFrQNBhZ2TFazrjdB+lAVobiUAqQs5spppG+ZPrO8tLjQR7Dr+jhHzS wSH3EaK+AdWwG47001ES4NaKFTAm2aZ6yWHVqSxP6Kz/KB5JpbnHTC05C1G6pYndQwdE Qwag== 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=lx5BmBC95dmjmIJXP3XVFwYVbr7vxLXanF8P7NwdV8qNFfteUxm+pnLgk0QFcbz9nD 1Xs220XGI8m4GzYnyMLOmxLOFhPXdxkWUmwq7vsrVybL0RstQxpn1icXrRSop75S3WN3 Ag3Nqv98250PCxlI1Lo9YqlpKrSCgulqYSa43LV70l3f5xbmTGP/XVL4hJUFN/asKdgC iTaZcnhI3yBziAM25iDEEsc06gW/gU6d1bYmjd3B91ALkZ6H6n0YhfwspUSDONwFzxDn sP95Z/m4G98oIJN25uyewIl7vRWNyM8votUcMPpqGL9QQfYmBiBL+FVaNMx2j3Cq9SEQ T/WA== X-Gm-Message-State: APjAAAXH+5y4M1NUpMAYMGIsSu6bN23B4MZG7IXeJCsuObK7LdobTobX /Dyaz13xLYT8x9uKOx9YloiIVA== X-Google-Smtp-Source: APXvYqx9WP5jwojRzuN71GCyy37AdeKNMFFLQmvHP0V1FQj1rrtvgopL0rffK6o4XmLQi+JfIgAZMQ== X-Received: by 2002:a1c:e714:: with SMTP id e20mr15426964wmh.143.1558697752051; Fri, 24 May 2019 04:35:52 -0700 (PDT) Received: from cbtest28.netronome.com ([217.38.71.146]) by smtp.gmail.com with ESMTPSA id x22sm2462902wmi.4.2019.05.24.04.35.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 24 May 2019 04:35:51 -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 v8 bpf-next 05/16] bpf: introduce new bpf prog load flags "BPF_F_TEST_RND_HI32" Date: Fri, 24 May 2019 12:35:15 +0100 Message-Id: <1558697726-4058-6-git-send-email-jiong.wang@netronome.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1558697726-4058-1-git-send-email-jiong.wang@netronome.com> References: <1558697726-4058-1-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: *