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=-10.4 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 D509FC433F4 for ; Mon, 27 Aug 2018 18:57:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 934AF208B9 for ; Mon, 27 Aug 2018 18:57:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="o9crLYXA" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 934AF208B9 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 S1727694AbeH0Wpo (ORCPT ); Mon, 27 Aug 2018 18:45:44 -0400 Received: from mail-yw1-f73.google.com ([209.85.161.73]:56396 "EHLO mail-yw1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727446AbeH0Wpn (ORCPT ); Mon, 27 Aug 2018 18:45:43 -0400 Received: by mail-yw1-f73.google.com with SMTP id v144-v6so9124285ywa.23 for ; Mon, 27 Aug 2018 11:57:53 -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=KBDYTwl+4YqOfnO5Qfg86x4cKuvMKrAYQHW8MjM7Sds=; b=o9crLYXA1KBVkHprU7iR4oojNCYfx0uxHyHSLNCkuQrKYrCnSBnaqMMyFELgVXd1NZ DAXXMej5rPOgAvVYzUelSVx7IIGxcrD9FAWTz9rULDc3e9Ac+TfzU2AcJ/5GGyVGnVKJ hS11XZbVar/Zr3KgB/yy7tXA93X55V8ZjgGKtfh+sn9FrvgVjJgFkPHLLa8nZQet3U9V n2de6p9ZUNe5uC2cMTEdz8g7WDzmcSLRfNTcOLaNa+u1aHrzpekIM0kxppOOijTsP5eS kPWizBb7tbRMa064qCQl6hhgL9mjFA94KU5fMeCVpvrZx4rUNkNhFKmvuh0GVRswxZ75 XuuA== 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=KBDYTwl+4YqOfnO5Qfg86x4cKuvMKrAYQHW8MjM7Sds=; b=lmNWHXtHIWKY7BO1DsVShDlkTqe6yJADu1CDN159W7/lvhbkx56JbFkZQZVAZKWFUp 4Hlk7mPjKEIK8DK5zh1kfy+/0USPzW6Z6xSVA97prTGenpY0zS5FHAtZiJHdkdvfdDoM nnwc82PIrDLSOihDFQiMFNTqV2XRRtCZEeP87+DqGTAzYhGseMLlgbhdcYAPgaAyiWeQ jGTCJJxL1i/h8rZ2hNujlfC5aiQ/yeW7jNtR/gDMjiGWZ6UbdRd3P6U3AaxnlIRWLiXx lkZBxBgMp5o6rlxtBXAoTKd9vJBeVkd5kwIqNiIbC/10H8ZP2bOP7KCbnXB7zV8awi/P KdRQ== X-Gm-Message-State: APzg51DYCGODPCEwnHG/5HAeh3fXKXVU0CqmF3oKCOBcdfVKKXvr0Zal FllUvFJNQi6Sf+B8lhaLBn1xTSTgHg== X-Google-Smtp-Source: ANB0VdYevvTK8UaxtYEQwxoCuHfWK0zoq9LG6T+yi/CM+Cq4Si26e92JZ4jvKH6PfCJcXKmEluyhASxfKQ== X-Received: by 2002:a81:a1c3:: with SMTP id y186-v6mr4485ywg.206.1535396273261; Mon, 27 Aug 2018 11:57:53 -0700 (PDT) Date: Mon, 27 Aug 2018 20:56:25 +0200 In-Reply-To: <20180827185631.163506-1-jannh@google.com> Message-Id: <20180827185631.163506-2-jannh@google.com> Mime-Version: 1.0 References: <20180827185631.163506-1-jannh@google.com> X-Mailer: git-send-email 2.19.0.rc0.228.g281dcd1b4d0-goog Subject: [PATCH v2 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, Tony Luck , Borislav Petkov , jannh@google.com Cc: linux-kernel@vger.kernel.org, dvyukov@google.com, linux-edac@vger.kernel.org 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 --- arch/x86/mm/fault.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index b9123c497e0a..2254a30533b9 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -44,17 +44,14 @@ 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; + /* + * To be potentially processing a kprobe fault and to be allowed to call + * kprobe_running(), we have to be non-preemptible. + */ + if (kprobes_built_in() && !user_mode(regs) && !preemptible() && + kprobe_running() && kprobe_fault_handler(regs, X86_TRAP_PF)) + return 1; + return 0; } /* -- 2.19.0.rc0.228.g281dcd1b4d0-goog