From patchwork Fri Nov 27 17:57:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brendan Jackman X-Patchwork-Id: 11937011 X-Patchwork-Delegate: bpf@iogearbox.net 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 F3210C3E8C5 for ; Fri, 27 Nov 2020 17:58:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A06192224A for ; Fri, 27 Nov 2020 17:58:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tIaLYwou" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732719AbgK0R5v (ORCPT ); Fri, 27 Nov 2020 12:57:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732681AbgK0R5v (ORCPT ); Fri, 27 Nov 2020 12:57:51 -0500 Received: from mail-qt1-x84a.google.com (mail-qt1-x84a.google.com [IPv6:2607:f8b0:4864:20::84a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB672C0613D2 for ; Fri, 27 Nov 2020 09:57:50 -0800 (PST) Received: by mail-qt1-x84a.google.com with SMTP id x62so235897qtd.11 for ; Fri, 27 Nov 2020 09:57:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=pCm5bSXPkdYGa8DRY20xR0eBkPwWiyvd1AYgQ0fdFE4=; b=tIaLYwouJp51q4LpdC5w6IxE4wvtbS/vWXbBRw2PKuDiSDRPyxx1bUK25Gbdt41+Fx gkYmyxooYOjjdPNUl16J0NlVinIY0MfAxd+Mut69Qa0jLOfu7ZAZk+BDKjAYyi79C+yg 20Lwa7gg9F3Tkbilhq4e+UBxxMCJFL50IPeczhuyV/0GcQo0xF54K5Dg0x5y5X5ekSKB 665yHxJEDdyTcsDSHpSOnRBg56ZHLKv3cL7qxQuX0hCXlQp/mBpxx06VPdIOJBkXoBBU 7aq2o+ACt8z0wgsQMpQOg/eo84fBNm00gfKu7bHs/e5XBA5+aDh9XtHf3OV2C+X+JiQT Pi+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=pCm5bSXPkdYGa8DRY20xR0eBkPwWiyvd1AYgQ0fdFE4=; b=icm7KKBYVvc+5QXTuggVpGScYGmZPUnF6nuy81Gf2VfEyDWzGZFihlrI+ovs+f3C8s FL20vjzQfWrd6Sbv8XjjpHxSe3OVMJqLGBIjnOZ5cJqDBiFLPT521+gE+Hx8HaqsafIh OUt/b7m9A2ZkjSRJgtNiRIpl3DvWK5p1RRkptuHtrdsQRBy3LPzWOqa00cSPEciUrxNz m51gQ0D6N6B7q66Jiy9pqxJ3hAPhrTrtQxDSbhpzLXfn8a7+ggxaZJ6vAFgntt1V0z7j hQgU5kEieOdI3HoPl0/Fc56HZi9+SRK4Tjx9XEmfYd/NRDvrnvenTOoHHTs1V8cWSSZ8 q5aw== X-Gm-Message-State: AOAM531UzM8Wqe0z8tBr1CYDjLYwhV0D+q9U+wVVDs0J2TSaHn4Ox0PE nc/gg7UzTWmSY67drgAXRHnWBAClMEsYI0HdJw5jvhJ8+su12zNrZhh6MJBOvBy7YEF+zp82Qbq jm0kKIMKdUBHqn2toIOF+kDq54/MleEryty2CjkKcekmP4KnH8usyNmjJn+tQSfQ= X-Google-Smtp-Source: ABdhPJzoTKHY6AOlzu8QYufpg7MnqU6ov6YK+vXzSz8+X+Yy2baFZMiE73UJR6EQRj7V14nEU91/iqJa66GTjw== Sender: "jackmanb via sendgmr" X-Received: from beeg.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:11db]) (user=jackmanb job=sendgmr) by 2002:ad4:4432:: with SMTP id e18mr9496712qvt.57.1606499869651; Fri, 27 Nov 2020 09:57:49 -0800 (PST) Date: Fri, 27 Nov 2020 17:57:26 +0000 In-Reply-To: <20201127175738.1085417-1-jackmanb@google.com> Message-Id: <20201127175738.1085417-2-jackmanb@google.com> Mime-Version: 1.0 References: <20201127175738.1085417-1-jackmanb@google.com> X-Mailer: git-send-email 2.29.2.454.gaff20da3a2-goog Subject: [PATCH v2 bpf-next 01/13] bpf: x86: Factor out emission of ModR/M for *(reg + off) From: Brendan Jackman To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Yonghong Song , Daniel Borkmann , KP Singh , Florent Revest , linux-kernel@vger.kernel.org, Jann Horn , Brendan Jackman Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net The case for JITing atomics is about to get more complicated. Let's factor out some common code to make the review and result more readable. NB the atomics code doesn't yet use the new helper - a subsequent patch will add its use as a side-effect of other changes. Signed-off-by: Brendan Jackman --- arch/x86/net/bpf_jit_comp.c | 42 +++++++++++++++++++++---------------- 1 file changed, 24 insertions(+), 18 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 796506dcfc42..94b17bd30e00 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -681,6 +681,27 @@ static void emit_mov_reg(u8 **pprog, bool is64, u32 dst_reg, u32 src_reg) *pprog = prog; } +/* Emit the ModR/M byte for addressing *(r1 + off) and r2 */ +static void emit_modrm_dstoff(u8 **pprog, u32 r1, u32 r2, int off) +{ + u8 *prog = *pprog; + int cnt = 0; + + if (is_imm8(off)) { + /* 1-byte signed displacement. + * + * If off == 0 we could skip this and save one extra byte, but + * special case of x86 R13 which always needs an offset is not + * worth the hassle + */ + EMIT2(add_2reg(0x40, r1, r2), off); + } else { + /* 4-byte signed displacement */ + EMIT1_off32(add_2reg(0x80, r1, r2), off); + } + *pprog = prog; +} + /* LDX: dst_reg = *(u8*)(src_reg + off) */ static void emit_ldx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off) { @@ -708,15 +729,7 @@ static void emit_ldx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off) EMIT2(add_2mod(0x48, src_reg, dst_reg), 0x8B); break; } - /* - * If insn->off == 0 we can save one extra byte, but - * special case of x86 R13 which always needs an offset - * is not worth the hassle - */ - if (is_imm8(off)) - EMIT2(add_2reg(0x40, src_reg, dst_reg), off); - else - EMIT1_off32(add_2reg(0x80, src_reg, dst_reg), off); + emit_modrm_dstoff(&prog, src_reg, dst_reg, off); *pprog = prog; } @@ -751,10 +764,7 @@ static void emit_stx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off) EMIT2(add_2mod(0x48, dst_reg, src_reg), 0x89); break; } - if (is_imm8(off)) - EMIT2(add_2reg(0x40, dst_reg, src_reg), off); - else - EMIT1_off32(add_2reg(0x80, dst_reg, src_reg), off); + emit_modrm_dstoff(&prog, dst_reg, src_reg, off); *pprog = prog; } @@ -1240,11 +1250,7 @@ st: if (is_imm8(insn->off)) goto xadd; case BPF_STX | BPF_XADD | BPF_DW: EMIT3(0xF0, add_2mod(0x48, dst_reg, src_reg), 0x01); -xadd: if (is_imm8(insn->off)) - EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off); - else - EMIT1_off32(add_2reg(0x80, dst_reg, src_reg), - insn->off); +xadd: emit_modrm_dstoff(&prog, dst_reg, src_reg, insn->off); break; /* call */