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=-10.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_MED,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 BD008C433F4 for ; Tue, 28 Aug 2018 20:14:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 75E972087E for ; Tue, 28 Aug 2018 20:14:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="QqjEy0pa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 75E972087E Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727317AbeH2AH6 (ORCPT ); Tue, 28 Aug 2018 20:07:58 -0400 Received: from mail-vk0-f73.google.com ([209.85.213.73]:38013 "EHLO mail-vk0-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727162AbeH2AH5 (ORCPT ); Tue, 28 Aug 2018 20:07:57 -0400 Received: by mail-vk0-f73.google.com with SMTP id d134-v6so1114570vkf.5 for ; Tue, 28 Aug 2018 13:14:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=uRAKHZlA0btsCxDvC9F6MjjKyQXLUpbtwbnShrkeMs8=; b=QqjEy0paB2ESV8Eq3Z0vETkQyMFWYL7kKtF/GF8hO4P+n/fyNdczSjh4I9yk7VBXvY CdhV263LIrzgGo+MzHtTLUaUlO3nB8ye5f7YrwPgbLec9ND8WyL3TClkV8zWEvQot1QC YDJ2LcFH7fE8hlvgDKcNHj+7L+QFJhbxV3CamRUr3H6aabclbqrGOtUn24Uli6u9w2sB a7qBwt5as4CNh3pVe6VdAO852f5kqRb4+n9ylOd4wZX/6AJILVnzc4TgZ82WUTcCU4Gp n2hdirYGHToTE8Bn1wxoIOSmqmdOPmgPnZRM7ghWxK/zE5SnF0mfpA0Dc2vaU802MtLJ q3tw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=uRAKHZlA0btsCxDvC9F6MjjKyQXLUpbtwbnShrkeMs8=; b=diP8vp5p4bW2+sei1bYWURKfQR8VBTlODJWWGUCdnSohR+NCB642GeZKgpuLXCCoxm IGXVAGj+1y0mGFpDf6ol1DGgZRG6cQxZbm8V59XTrIwcAT6gYNAcXbtwnriE/hHaE/+f oKPAUdz8peQyaMWiGLun67eg3kARyDJGifzLc6CG0JqjvUjLfDYBWazw+zsVnNKxE0h9 N9gKllj/TW/jtmExP0wNbmKtJipZTe3qtXv+DhJEh6St14pzuhAOy10izK+5AngbZY0Q iosK+BEgXqV1Uz+DJCPd3T0RHjU/TxkTzRyMipJu9LqzYw+uIx0n+e8Cib25Z7gv/6s1 BFEA== X-Gm-Message-State: APzg51DPcS2JtmCv8GsczmGLczo6RpaiT8zuH+gwuCbiH5zqBOVq6byJ dBaMEXI6Aj1dcORXf87pMdzpPAz4mA== X-Google-Smtp-Source: ANB0VdZp/YDJc9C/v0lNpho7kK8NpP0tyQo06S1Yg8u9D8Ds1SiTDfbf4uwei9wnD4CvG4s+hIq1EkqCog== X-Received: by 2002:a1f:d382:: with SMTP id k124-v6mr1430418vkg.14.1535487281915; Tue, 28 Aug 2018 13:14:41 -0700 (PDT) Date: Tue, 28 Aug 2018 22:14:15 +0200 In-Reply-To: <20180828201421.157735-1-jannh@google.com> Message-Id: <20180828201421.157735-2-jannh@google.com> Mime-Version: 1.0 References: <20180828201421.157735-1-jannh@google.com> X-Mailer: git-send-email 2.19.0.rc0.228.g281dcd1b4d0-goog Subject: [PATCH v3 1/7] x86: refactor kprobes_fault() like kprobe_exceptions_notify() From: Jann Horn To: Kees Cook , Thomas Gleixner , Ingo Molnar , x86@kernel.org, Andy Lutomirski , kernel-hardening@lists.openwall.com, jannh@google.com Cc: linux-kernel@vger.kernel.org, dvyukov@google.com, Masami Hiramatsu , "Naveen N. Rao" , Anil S Keshavamurthy , "David S. Miller" , Alexander Viro , linux-fsdevel@vger.kernel.org, Borislav Petkov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an extension of commit b506a9d08bae ("x86: code clarification patch to Kprobes arch code"). As that commit explains, even though kprobe_running() can't be called with preemption enabled, you don't have to disable preemption - if preemption is on, you can't be in a kprobe. Also, use X86_TRAP_PF instead of 14. Signed-off-by: Jann Horn --- v3: - avoid unnecessary branch on return value and split up the checks (Borislav Petkov) arch/x86/mm/fault.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index b9123c497e0a..bcdaae1d5bf5 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -44,17 +44,19 @@ kmmio_fault(struct pt_regs *regs, unsigned long addr) static nokprobe_inline int kprobes_fault(struct pt_regs *regs) { - int ret = 0; - - /* kprobe_running() needs smp_processor_id() */ - if (kprobes_built_in() && !user_mode(regs)) { - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, 14)) - ret = 1; - preempt_enable(); - } - - return ret; + if (!kprobes_built_in()) + return 0; + if (user_mode(regs)) + return 0; + /* + * To be potentially processing a kprobe fault and to be allowed to call + * kprobe_running(), we have to be non-preemptible. + */ + if (preemptible()) + return 0; + if (!kprobe_running()) + return 0; + return kprobe_fault_handler(regs, X86_TRAP_PF); } /* -- 2.19.0.rc0.228.g281dcd1b4d0-goog