Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761512Ab3EAP1Q (ORCPT ); Wed, 1 May 2013 11:27:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60500 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754134Ab3EAP07 (ORCPT ); Wed, 1 May 2013 11:26:59 -0400 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 , Stephane Eranian Subject: [PATCH 2/4] signal x86: Clear RF EFLAGS bit for signal handler Date: Wed, 1 May 2013 17:25:42 +0200 Message-Id: <1367421944-19082-3-git-send-email-jolsa@redhat.com> In-Reply-To: <1367421944-19082-1-git-send-email-jolsa@redhat.com> References: <1367421944-19082-1-git-send-email-jolsa@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1838 Lines: 51 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 Tested-by: Oleg Nesterov Reviewed-by: Frederic Weisbecker 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 Cc: Stephane Eranian --- arch/x86/kernel/signal.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 9df4c0b..cb12fc9 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -665,6 +665,12 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs) */ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/