From patchwork Wed May 1 14:43:49 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiong Wang X-Patchwork-Id: 1093695 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="gVw6VbES"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 44vLkq6N6Yz9s9y for ; Thu, 2 May 2019 00:44:19 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726970AbfEAOoS (ORCPT ); Wed, 1 May 2019 10:44:18 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:45019 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726506AbfEAOoQ (ORCPT ); Wed, 1 May 2019 10:44:16 -0400 Received: by mail-wr1-f67.google.com with SMTP id c5so24797254wrs.11 for ; Wed, 01 May 2019 07:44:14 -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=K4gLqJ4SgDOsgXMmICWdVA0zCxYikPtUo1d3XLqhgFA=; b=gVw6VbES46XLZdd8b3uLEiFoKT3v3WflQffUMx/vxZQTf0+fyQnsCPTsmCJooprTk0 v3exsBY38qssZRNTV/SSJkJYmdRiNjmFcytZa4nOq1ScFYq6fMEVSUJE0KGc7O7WUpL5 jzvw5F5rgUhVK0k05RTvIkaLTgXwWDcN0eEmjPfZIaTkaGjdhrfp3QfC5/zGoIWQKWip 0SazZNrmqwKpgJuk64nzj0GlA/m+4eu1P/HSbskV2cAgjE43rpwThIUXjToy0XDNJcRw 7EwIJaztBNCGc4k1YzzO/rq4JRQ6MPmI5oTJ1TVFWa7x4LU3uSp/TdtjjdUxg6SUJ5Sg DCfA== 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=K4gLqJ4SgDOsgXMmICWdVA0zCxYikPtUo1d3XLqhgFA=; b=O9BdjD0XnIqlQvzyzqd2AzUuZJ9mWX0se9nZKHAWfH9YAMfSN58LRAKKpSU0XP18IM rAckIsh031bMeZpSc0mwE01bOgN9uEigmtW7sUN8R00C+UMNKtltDPTSKCdnpHmxbVt0 O5dHkTQU2Bdo8FPiK0bEzJpZynVeOa9IR52DNcZlSj4Ipnp2IOSA2o0/lc6yCUWpQZOH DJcdh6Q8ZRyOoFV0goRhtWAO6P0pFb7ey0JJdfsHwGVvEJbKxJdWXKT/bdMqCppzGIm+ 9FQsS2rdi/6bxnOm/qNanEfwyHbeIJ/TvKBPKAaX7jXu8Jlpni8RLmQfCHiDxX0LmstK LzTQ== X-Gm-Message-State: APjAAAWP+lNx/LUzHcqFFqD0uG2HhN+hP3mRGl1kEKajxrF9SXZrva+J 9IGKoC06AAgHCDDu4nbQfGJZ+g== X-Google-Smtp-Source: APXvYqwc9tGZL5fZiZ1uX9UHtpeG3SYZNVw7wRli/9ijMCGMFK3dl0f5g9V9i0s7bmHnSOBoRHtUSA== X-Received: by 2002:adf:e387:: with SMTP id e7mr4633925wrm.17.1556721853950; Wed, 01 May 2019 07:44:13 -0700 (PDT) Received: from cbtest28.netronome.com ([217.38.71.146]) by smtp.gmail.com with ESMTPSA id g10sm36164976wrq.2.2019.05.01.07.44.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 01 May 2019 07:44:13 -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, Jiong Wang Subject: [PATCH v5 bpf-next 04/17] bpf: introduce new alu insn BPF_ZEXT for explicit zero extension Date: Wed, 1 May 2019 15:43:49 +0100 Message-Id: <1556721842-29836-5-git-send-email-jiong.wang@netronome.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1556721842-29836-1-git-send-email-jiong.wang@netronome.com> References: <1556721842-29836-1-git-send-email-jiong.wang@netronome.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This patch introduce new alu32 insn BPF_ZEXT, and allocate the unused opcode 0xe0 to it. Compared with the other alu32 insns, zero extension on low 32-bit is the only semantics for this instruction. It also allows various JIT back-ends to do optimal zero extension code-gen. BPF_ZEXT is supposed to be encoded with BPF_ALU only, and is supposed to be generated by the latter 32-bit optimization code inside verifier for those arches that do not support hardware implicit zero extension only. It is not supposed to be used in user's program directly at the moment. Therefore, no need to recognize it inside generic verification code. It just need to be supported for execution on interpreter or related JIT back-ends. Signed-off-by: Jiong Wang --- Documentation/networking/filter.txt | 10 ++++++++++ include/uapi/linux/bpf.h | 3 +++ kernel/bpf/core.c | 4 ++++ tools/include/uapi/linux/bpf.h | 3 +++ 4 files changed, 20 insertions(+) diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt index 319e5e0..1cb3e42 100644 --- a/Documentation/networking/filter.txt +++ b/Documentation/networking/filter.txt @@ -903,6 +903,16 @@ If BPF_CLASS(code) == BPF_ALU or BPF_ALU64 [ in eBPF ], BPF_OP(code) is one of: BPF_MOV 0xb0 /* eBPF only: mov reg to reg */ BPF_ARSH 0xc0 /* eBPF only: sign extending shift right */ BPF_END 0xd0 /* eBPF only: endianness conversion */ + BPF_ZEXT 0xe0 /* eBPF BPF_ALU only: zero-extends low 32-bit */ + +Compared with BPF_ALU | BPF_MOV which zero-extends low 32-bit implicitly, +BPF_ALU | BPF_ZEXT zero-extends low 32-bit explicitly. Such zero extension is +not the main semantics for the prior, but is for the latter. Therefore, JIT +optimizer could optimize out the zero extension for the prior when it is +concluded safe to do so, but should never do such optimization for the latter. +LLVM compiler won't generate BPF_ZEXT, and hand written assembly is not supposed +to use it. Verifier 32-bit optimization pass, which removes zero extension +semantics from the other BPF_ALU instructions, is the only place generates it. If BPF_CLASS(code) == BPF_JMP or BPF_JMP32 [ in eBPF ], BPF_OP(code) is one of: diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 72336ba..22ccdf4 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -32,6 +32,9 @@ #define BPF_FROM_LE BPF_TO_LE #define BPF_FROM_BE BPF_TO_BE +/* zero extend low 32-bit */ +#define BPF_ZEXT 0xe0 + /* jmp encodings */ #define BPF_JNE 0x50 /* jump != */ #define BPF_JLT 0xa0 /* LT is unsigned, '<' */ diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 2792eda..ee8703d 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1152,6 +1152,7 @@ EXPORT_SYMBOL_GPL(__bpf_call_base); INSN_2(ALU, NEG), \ INSN_3(ALU, END, TO_BE), \ INSN_3(ALU, END, TO_LE), \ + INSN_2(ALU, ZEXT), \ /* Immediate based. */ \ INSN_3(ALU, ADD, K), \ INSN_3(ALU, SUB, K), \ @@ -1352,6 +1353,9 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u64 *stack) ALU64_NEG: DST = -DST; CONT; + ALU_ZEXT: + DST = (u32) DST; + CONT; ALU_MOV_X: DST = (u32) SRC; CONT; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 72336ba..22ccdf4 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -32,6 +32,9 @@ #define BPF_FROM_LE BPF_TO_LE #define BPF_FROM_BE BPF_TO_BE +/* zero extend low 32-bit */ +#define BPF_ZEXT 0xe0 + /* jmp encodings */ #define BPF_JNE 0x50 /* jump != */ #define BPF_JLT 0xa0 /* LT is unsigned, '<' */