From patchwork Fri Nov 27 17:57:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brendan Jackman X-Patchwork-Id: 11937015 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 1CDB9C63798 for ; Fri, 27 Nov 2020 17:58:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D26372224C 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="HjJkNd/F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732738AbgK0R5x (ORCPT ); Fri, 27 Nov 2020 12:57:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732731AbgK0R5x (ORCPT ); Fri, 27 Nov 2020 12:57:53 -0500 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0D57C0613D2 for ; Fri, 27 Nov 2020 09:57:52 -0800 (PST) Received: by mail-qk1-x749.google.com with SMTP id d206so4119141qkc.23 for ; Fri, 27 Nov 2020 09:57:52 -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=S3LKp+3RvK8OZkmGe150smJLkvcUKra31qzmBdRpcwc=; b=HjJkNd/Fcb7hlI25N2/0RZaPOeJLmob9416QnTRAdWKyICh8nlL4N42gT7uYToO16V USLz0UptmPjQlEwvmgho10Ctx+6t/NUOYRkjpaHSs1tXiHAuEyx0ZT9LV8XtNL2aya/Y OPqXGnne4x7klTAiwv2z72/uksfWLkcx0t7tCr0/7WB8rUa9Xd16zdIYNBEhyk5oRYGB M2YonpjfV6Ujm7xik6fhgGm9CIFXiDZNT8bXQvkfBmtRtrpi3/w3rUL+iCDzq+M1sSu9 4uzjdd34FZh4N8WzgTiXMirD6XpfZHgE98Xvtwh1wqemySCXDfdx4ar6Lm+Pr4qNrKES xmIw== 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=S3LKp+3RvK8OZkmGe150smJLkvcUKra31qzmBdRpcwc=; b=mW617/JHXIuqHlZ5Ridhkk8NnNFJ7yn1Y3ULsa5PJam//JqSQ7Y6n/n9WG3FEr/1Wy Ev23/UzsMYsOvdeBSw3peqrBH6Wa2fGihVzkdjuhPINMeE8TF4gNLVKfvCTxIK/+NBDx VvNtENT4FDhn4wJfLc4XgTIf8LC8BgRh0wgE5bvGqeriohojL016SY+mjjnzEMvH5PVX A3J7IaPR7w+fhmmus11YK2X/9r03eP7tzwRV9OefLd3AxjDqSOqS6TGY6fOlx4nw567O oas9xs5L4ggpzmV3t2IuCJxpRaSTitN82+M9hp+OpHkf2htqkq2d7V3a6g2/OvhI6MS8 6EzA== X-Gm-Message-State: AOAM531vc2ULhp3FPB92oXoJmyALbolsMXo71/lCSV9UvLAIzNtHU+jc ZkU/a3X2s/lStXIfftl4ebzwabjghkhA5jSlJyB5CkV1/LESlrai0oD6hthX3VOahOKQ5assi/3 rli7l0s7uQ+w+JIecSI+TrnaAM4bb0VZWZeMkTYm6lkB+7xGtyri2PJYmwoYoGw4= X-Google-Smtp-Source: ABdhPJyyHmArdB3e3yTqjlnMow5d9+BjTkDGqoBU9a+C+qyn1UIo8b9nMbPDQY8AxWcN+k392VZX9ao0Cr7r+A== 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:a05:6214:2b4:: with SMTP id m20mr9656499qvv.34.1606499871986; Fri, 27 Nov 2020 09:57:51 -0800 (PST) Date: Fri, 27 Nov 2020 17:57:27 +0000 In-Reply-To: <20201127175738.1085417-1-jackmanb@google.com> Message-Id: <20201127175738.1085417-3-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 02/13] bpf: x86: Factor out emission of REX byte 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 JIT case for encoding atomic ops is about to get more complicated. In order to make the review & resulting code easier, let's factor out some shared helpers. Signed-off-by: Brendan Jackman --- arch/x86/net/bpf_jit_comp.c | 39 ++++++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 16 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 94b17bd30e00..a839c1a54276 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -702,6 +702,21 @@ static void emit_modrm_dstoff(u8 **pprog, u32 r1, u32 r2, int off) *pprog = prog; } +/* + * Emit a REX byte if it will be necessary to address these registers + */ +static void maybe_emit_rex(u8 **pprog, u32 reg_rm, u32 reg_reg, bool wide) +{ + u8 *prog = *pprog; + int cnt = 0; + + if (wide) + EMIT1(add_2mod(0x48, reg_rm, reg_reg)); + else if (is_ereg(reg_rm) || is_ereg(reg_reg)) + EMIT1(add_2mod(0x40, reg_rm, reg_reg)); + *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) { @@ -854,10 +869,8 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, case BPF_OR: b2 = 0x09; break; case BPF_XOR: b2 = 0x31; break; } - if (BPF_CLASS(insn->code) == BPF_ALU64) - EMIT1(add_2mod(0x48, dst_reg, src_reg)); - else if (is_ereg(dst_reg) || is_ereg(src_reg)) - EMIT1(add_2mod(0x40, dst_reg, src_reg)); + maybe_emit_rex(&prog, dst_reg, src_reg, + BPF_CLASS(insn->code) == BPF_ALU64); EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg)); break; @@ -1301,20 +1314,16 @@ xadd: emit_modrm_dstoff(&prog, dst_reg, src_reg, insn->off); case BPF_JMP32 | BPF_JSGE | BPF_X: case BPF_JMP32 | BPF_JSLE | BPF_X: /* cmp dst_reg, src_reg */ - if (BPF_CLASS(insn->code) == BPF_JMP) - EMIT1(add_2mod(0x48, dst_reg, src_reg)); - else if (is_ereg(dst_reg) || is_ereg(src_reg)) - EMIT1(add_2mod(0x40, dst_reg, src_reg)); + maybe_emit_rex(&prog, dst_reg, src_reg, + BPF_CLASS(insn->code) == BPF_JMP); EMIT2(0x39, add_2reg(0xC0, dst_reg, src_reg)); goto emit_cond_jmp; case BPF_JMP | BPF_JSET | BPF_X: case BPF_JMP32 | BPF_JSET | BPF_X: /* test dst_reg, src_reg */ - if (BPF_CLASS(insn->code) == BPF_JMP) - EMIT1(add_2mod(0x48, dst_reg, src_reg)); - else if (is_ereg(dst_reg) || is_ereg(src_reg)) - EMIT1(add_2mod(0x40, dst_reg, src_reg)); + maybe_emit_rex(&prog, dst_reg, src_reg, + BPF_CLASS(insn->code) == BPF_JMP); EMIT2(0x85, add_2reg(0xC0, dst_reg, src_reg)); goto emit_cond_jmp; @@ -1350,10 +1359,8 @@ xadd: emit_modrm_dstoff(&prog, dst_reg, src_reg, insn->off); case BPF_JMP32 | BPF_JSLE | BPF_K: /* test dst_reg, dst_reg to save one extra byte */ if (imm32 == 0) { - if (BPF_CLASS(insn->code) == BPF_JMP) - EMIT1(add_2mod(0x48, dst_reg, dst_reg)); - else if (is_ereg(dst_reg)) - EMIT1(add_2mod(0x40, dst_reg, dst_reg)); + maybe_emit_rex(&prog, dst_reg, dst_reg, + BPF_CLASS(insn->code) == BPF_JMP); EMIT2(0x85, add_2reg(0xC0, dst_reg, dst_reg)); goto emit_cond_jmp; }