From mboxrd@z Thu Jan 1 00:00:00 1970 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 11E88C433B4 for ; Thu, 6 May 2021 19:44:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD15961289 for ; Thu, 6 May 2021 19:44:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235821AbhEFTpL (ORCPT ); Thu, 6 May 2021 15:45:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33562 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235721AbhEFTox (ORCPT ); Thu, 6 May 2021 15:44:53 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1270EC06138B for ; Thu, 6 May 2021 12:43:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=zN+cgK9L1vGhTGBZmLlXfmugO1t8jyzZ97aV4L6C/NU=; b=dhsaPUJqgadKCDfmfm66r66qwK PY8R4d9hWpWSgaJUfCQRZWBJqCcz46dOVgiNIl5vhJLWfLmesugoJ8iUMs1bj8/Pq+BjT3VJ5Ua27 4gEkrcKTWNIvyUmbVJxB3rMMSiJPKd+z4TTPaU1SBhQNZHo6cdyIVMlwnY5nSmGpgT98HN0IvdtaM hgh+Cm8/qwQgrR672OI3/lgJfaIOwzRZJQ4DlErLQD5liCdra99VufSIULHDsfYvH9Tb3KYWJhqQG miC/Rbh755Z0PA1hdgznatBVs3eHlYfce9kuZuqL8o7M3IhCfqXMlwH1Xq6aFa6PObqD/gbVSFIxE wrdLWlJQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lejtS-002ADF-Cw; Thu, 06 May 2021 19:42:48 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 18A3E300359; Thu, 6 May 2021 21:42:39 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id BF10820B96F8E; Thu, 6 May 2021 21:42:38 +0200 (CEST) Message-ID: <20210506194157.967034497@infradead.org> User-Agent: quilt/0.66 Date: Thu, 06 May 2021 21:34:01 +0200 From: Peter Zijlstra To: x86@kernel.org, jpoimboe@redhat.com, jbaron@akamai.com, rostedt@goodmis.org, ardb@kernel.org Cc: linux-kernel@vger.kernel.org, peterz@infradead.org Subject: [PATCH 09/13] jump_label,x86: Emit short JMP References: <20210506193352.719596001@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now that we can patch short JMP/NOP, allow the compiler/assembler to emit short JMP instructions. There is no way to have the assembler emit short NOPs based on the potential displacement, so leave those long for now. Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/include/asm/jump_label.h | 3 +-- arch/x86/kernel/jump_label.c | 8 +++++++- 2 files changed, 8 insertions(+), 3 deletions(-) --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -35,8 +35,7 @@ static __always_inline bool arch_static_ static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch) { asm_volatile_goto("1:" - ".byte 0xe9 \n\t" - ".long %l[l_yes] - (. + 4) \n\t" + "jmp %l[l_yes]\n\t" JUMP_TABLE_ENTRY : : "i" (key), "i" (branch) : : l_yes); --- a/arch/x86/kernel/jump_label.c +++ b/arch/x86/kernel/jump_label.c @@ -15,12 +15,18 @@ #include #include #include +#include #define JUMP_LABEL_NOP_SIZE JMP32_INSN_SIZE int arch_jump_entry_size(struct jump_entry *entry) { - return JMP32_INSN_SIZE; + struct insn insn = {}; + + insn_decode_kernel(&insn, (void *)jump_entry_code(entry)); + BUG_ON(insn.length != 2 && insn.length != 5); + + return insn.length; } struct jump_label_patch {