From patchwork Mon Dec 7 16:07:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brendan Jackman X-Patchwork-Id: 11956271 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=ham 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 881A8C1B087 for ; Mon, 7 Dec 2020 16:09:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 678DD23750 for ; Mon, 7 Dec 2020 16:09:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727622AbgLGQJg (ORCPT ); Mon, 7 Dec 2020 11:09:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55770 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727620AbgLGQJg (ORCPT ); Mon, 7 Dec 2020 11:09:36 -0500 Received: from mail-wm1-x34a.google.com (mail-wm1-x34a.google.com [IPv6:2a00:1450:4864:20::34a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08A06C0611C5 for ; Mon, 7 Dec 2020 08:08:19 -0800 (PST) Received: by mail-wm1-x34a.google.com with SMTP id a205so4245365wme.9 for ; Mon, 07 Dec 2020 08:08:18 -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=kgZtScldrNgFhrDY/e+Xd6nj0yddjgbqe7qwF3mWjO8=; b=pyjvyLWOa1EQCy1NoYOD2h7b7N4pAa2L10D9jR+mlztus7GqiVpqFCrW2Y1d562f0O kQAdf9qVjQEwI12nc6uOEiYrNJybfqpP4JrnFTYuivosOGqpYgXkxwRIm7IMX6saYNv9 sgoP9FRqrlCfqlwGYNu/sPw8wk5MrzvqyC63JBOfeFWX56/JrPOmUCOxiwBwUhyeQtVx iG187tYfsbgIf5eYaOn1GBicp24kE2Jiv4CCX1NhwtEcN+sph2d/CnregvSoxFosce0s DULvNbrfMa1mgPKMLAFOSxFXhL9Q5q+tlAme5zpKZhV/Iy2GnGND3z/AACjilSV9RcoQ 1ztQ== 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=kgZtScldrNgFhrDY/e+Xd6nj0yddjgbqe7qwF3mWjO8=; b=P984K6NJHZb2PH28acEEvGJN8fGPynkhnPbdCxgVXbKo5If6TOgavyPU5e+/s9dB0u YRqalJDA2bmhPMvYYT5Q+h3eK7g5dPIfVnhzMwDYcs089OMPFO7dufLyhztYdGEBrrq/ LAvwDnZuMd/trVISYfa8zUEsvz/LcXh/Z5Xt2VRXD3WuTveKySS84NaBvLP5WWtSKO9l VLqU+TnppqJgA7lmAz9hbI+HaOGhzzC+W086GCcSf2Pp04m7s8EtBvaD499PHmt8vI/j EXfjgTZXg+UptovrwRkFMFWruyg2Qt4kJIljrZ40DJMATC3je4qmZcqOnyEGFOA2pBCM TEDg== X-Gm-Message-State: AOAM533gZbZp0pwBStdLf/Fmkd5GPoZ4Sa6hT4aNTDNoKQRUJopKhaQ0 RN+AF+5RpZ/mGAMvJaL8SFuewLI9rj1wQ9pPpasLayl1JcOTzucPe6YVTOi3Bxomp0VTE3TVMW4 q62E8oKKcvUSpHQ82IiIZdjNcr7CUHRdtg+TTwzDfIz2a8vpI87BKfA9b4lOKdxc= X-Google-Smtp-Source: ABdhPJwb/AJgi6+k9jvdTCL+fgh9ommb1FTsfZNUsVYyPrgMHq9UoGom1hsGqPCSY1iU6sARXQe4oniJQbk+HQ== 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:a1c:791a:: with SMTP id l26mr54795wme.1.1607357296984; Mon, 07 Dec 2020 08:08:16 -0800 (PST) Date: Mon, 7 Dec 2020 16:07:25 +0000 In-Reply-To: <20201207160734.2345502-1-jackmanb@google.com> Message-Id: <20201207160734.2345502-3-jackmanb@google.com> Mime-Version: 1.0 References: <20201207160734.2345502-1-jackmanb@google.com> X-Mailer: git-send-email 2.29.2.576.ga3fc446d84-goog Subject: [PATCH bpf-next v4 02/11] 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 Acked-by: John Fastabend --- 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 cc818ed7c2b9..7106cfd10ba6 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -702,6 +702,21 @@ static void emit_insn_suffix(u8 **pprog, u32 ptr_reg, u32 val_reg, int off) *pprog = prog; } +/* + * Emit a REX byte if it will be necessary to address these registers + */ +static void maybe_emit_mod(u8 **pprog, u32 dst_reg, u32 src_reg, bool is64) +{ + u8 *prog = *pprog; + int cnt = 0; + + if (is64) + 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)); + *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_mod(&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_mod(&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_mod(&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_mod(&prog, dst_reg, dst_reg, + BPF_CLASS(insn->code) == BPF_JMP); EMIT2(0x85, add_2reg(0xC0, dst_reg, dst_reg)); goto emit_cond_jmp; }