From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754459AbaKNHQP (ORCPT ); Fri, 14 Nov 2014 02:16:15 -0500 Received: from e28smtp02.in.ibm.com ([122.248.162.2]:56430 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754218AbaKNHQN (ORCPT ); Fri, 14 Nov 2014 02:16:13 -0500 Date: Fri, 14 Nov 2014 12:45:59 +0530 From: Srikar Dronamraju To: Andy Lutomirski Cc: Borislav Petkov , X86 ML , "linux-kernel@vger.kernel.org" , Peter Zijlstra , Oleg Nesterov , Tony Luck , Andi Kleen Subject: Re: [PATCH v2 2/2] uprobes, x86: Fix _TIF_UPROBE vs _TIF_NOTIFY_RESUME Message-ID: <20141114071559.GC12682@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <2beb5abca257e5b5f37420f5d85361e5e197824b.1415917623.git.luto@amacapital.net> <20141114060848.GB12682@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14111407-0005-0000-0000-0000021F4780 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andy Lutomirski [2014-11-13 23:01:12]: > On Thu, Nov 13, 2014 at 10:08 PM, Srikar Dronamraju > wrote: > > * Andy Lutomirski [2014-11-13 14:31:21]: > > > >> x86 call do_notify_resume on paranoid returns if TIF_UPROBE is set > >> but not on non-paranoid returns. I suspect that this is a mistake > >> and that the code only works because int3 is paranoid. > >> > >> Setting _TIF_NOTIFY_RESUME in the uprobe code was probably a > >> workaround for the x86 bug. With that bug fixed, we can remove > > > >> _TIF_NOTIFY_RESUME from the uprobes code. > >> > >> Cc: Srikar Dronamraju > >> Reported-by: Oleg Nesterov > >> Signed-off-by: Andy Lutomirski > >> --- > >> arch/x86/include/asm/thread_info.h | 2 +- > >> kernel/events/uprobes.c | 1 - > >> 2 files changed, 1 insertion(+), 2 deletions(-) > >> > >> diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h > >> index 854053889d4d..547e344a6dc6 100644 > >> --- a/arch/x86/include/asm/thread_info.h > >> +++ b/arch/x86/include/asm/thread_info.h > >> @@ -141,7 +141,7 @@ struct thread_info { > >> /* Only used for 64 bit */ > >> #define _TIF_DO_NOTIFY_MASK \ > >> (_TIF_SIGPENDING | _TIF_MCE_NOTIFY | _TIF_NOTIFY_RESUME | \ > >> - _TIF_USER_RETURN_NOTIFY) > >> + _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE) > > > > > > The comment above says only for 64 bit. So would this still work for > > i386? > > > > i386 seems to look at _TIF_WORK_MASK (which includes _TIF_UPROBE) for > everything except syscalls and at _TIF_WORK_SYSCALL_EXIT for syscall > return (which does not include _TIF_UPROBE). Is that okay? > Ok.. That expains (please add my ack to your v3) Acked-by: Srikar Dronamraju > --Andy > > >> > >> /* flags to check in __switch_to() */ > >> #define _TIF_WORK_CTXSW \ > >> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > >> index 1d0af8a2c646..ed8f2cde34c5 100644 > >> --- a/kernel/events/uprobes.c > >> +++ b/kernel/events/uprobes.c > >> @@ -1640,7 +1640,6 @@ bool uprobe_deny_signal(void) > >> if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { > >> utask->state = UTASK_SSTEP_TRAPPED; > >> set_tsk_thread_flag(t, TIF_UPROBE); > >> - set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); > >> } > >> } > >> > >> -- > >> 1.9.3 > >> > > > > -- > > Thanks and Regards > > Srikar Dronamraju > > > > > > -- > Andy Lutomirski > AMA Capital Management, LLC > -- Thanks and Regards Srikar Dronamraju