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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 3223CC04EB8 for ; Thu, 6 Dec 2018 22:19:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 001E620868 for ; Thu, 6 Dec 2018 22:19:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 001E620868 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.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 S1726228AbeLFWTj (ORCPT ); Thu, 6 Dec 2018 17:19:39 -0500 Received: from mga06.intel.com ([134.134.136.31]:39985 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726119AbeLFWTb (ORCPT ); Thu, 6 Dec 2018 17:19:31 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Dec 2018 14:19:28 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,324,1539673200"; d="scan'208";a="99313300" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.154]) by orsmga008.jf.intel.com with ESMTP; 06 Dec 2018 14:19:28 -0800 From: Sean Christopherson To: Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, Dave Hansen , Peter Zijlstra Cc: "H. Peter Anvin" , linux-kernel@vger.kernel.org, Andy Lutomirski , Jarkko Sakkinen , Josh Triplett Subject: [RFC PATCH v2 3/4] x86/traps: Attempt to fixup exceptions in vDSO before signaling Date: Thu, 6 Dec 2018 14:19:21 -0800 Message-Id: <20181206221922.31012-4-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181206221922.31012-1-sean.j.christopherson@intel.com> References: <20181206221922.31012-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Call fixup_vdso_exception() in all trap flows that generate signals to userspace immediately prior to generating any such signal. If the exception is fixed, return cleanly and do not generate a signal. The goal of vDSO fixup is not to fixup all faults, nor is it to avoid all signals, but rather to report faults directly to userspace when the fault would otherwise directly result in a signal being sent to the process. Suggested-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Jarkko Sakkinen Cc: Dave Hansen Cc: Josh Triplett Signed-off-by: Sean Christopherson --- arch/x86/kernel/traps.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 9b7c4ca8f0a7..f813481a85ff 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -61,6 +61,7 @@ #include #include #include +#include #ifdef CONFIG_X86_64 #include @@ -223,6 +224,10 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, const char *str, tsk->thread.error_code = error_code; tsk->thread.trap_nr = trapnr; + if (user_mode(regs) && + fixup_vdso_exception(regs, trapnr, error_code, 0)) + return 0; + return -1; } @@ -563,6 +568,9 @@ do_general_protection(struct pt_regs *regs, long error_code) tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_GP; + if (fixup_vdso_exception(regs, X86_TRAP_GP, error_code, 0)) + return; + show_signal(tsk, SIGSEGV, "", desc, regs, error_code); force_sig(SIGSEGV, tsk); @@ -791,6 +799,10 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code) goto exit; } + if (user_mode(regs) && + fixup_vdso_exception(regs, X86_TRAP_DB, error_code, 0)) + goto exit; + if (WARN_ON_ONCE((dr6 & DR_STEP) && !user_mode(regs))) { /* * Historical junk that used to handle SYSENTER single-stepping. @@ -854,6 +866,9 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr) if (!si_code) return; + if (fixup_vdso_exception(regs, trapnr, error_code, 0)) + return; + force_sig_fault(SIGFPE, si_code, (void __user *)uprobe_get_trap_addr(regs), task); } -- 2.19.2