From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752299Ab3CASMg (ORCPT ); Fri, 1 Mar 2013 13:12:36 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43786 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752155Ab3CASMb (ORCPT ); Fri, 1 Mar 2013 13:12:31 -0500 From: Jiri Olsa To: linux-kernel@vger.kernel.org Cc: Jiri Olsa , Thomas Gleixner , "H. Peter Anvin" , Andi Kleen , Oleg Nesterov , Arnaldo Carvalho de Melo , Peter Zijlstra , Ingo Molnar , Paul Mackerras , Corey Ashford , Frederic Weisbecker , Vince Weaver Subject: [PATCH 2/5] signal x86: Clear RF EFLAGS bit for signal handler Date: Fri, 1 Mar 2013 19:11:49 +0100 Message-Id: <1362161512-16803-3-git-send-email-jolsa@redhat.com> In-Reply-To: <1362161512-16803-1-git-send-email-jolsa@redhat.com> References: <1362161512-16803-1-git-send-email-jolsa@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Clearing RF EFLAGS bit for signal handler. The reason is, that this flag is set by debug exception code to prevent the recursive exception entry. Leaving it set for signal handler might prevent debug exception of the signal handler itself. Signed-off-by: Jiri Olsa Cc: Thomas Gleixner Cc: H. Peter Anvin Cc: Andi Kleen Cc: Oleg Nesterov Cc: Arnaldo Carvalho de Melo Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Paul Mackerras Cc: Corey Ashford Cc: Frederic Weisbecker Cc: Vince Weaver --- arch/x86/kernel/signal.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index b6fe116..e273571 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -726,6 +726,13 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, regs->flags &= ~X86_EFLAGS_DF; /* + * Clear RF when entering the signal handler, because + * it might disable possible debug exception from the + * signal handler. + */ + regs->flags &= ~X86_EFLAGS_RF; + + /* * Clear TF when entering the signal handler, but * notify any tracer that was single-stepping it. * The tracer may want to single-step inside the -- 1.7.11.7