From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759134AbZCOT51 (ORCPT ); Sun, 15 Mar 2009 15:57:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757378AbZCOT45 (ORCPT ); Sun, 15 Mar 2009 15:56:57 -0400 Received: from mail-ew0-f177.google.com ([209.85.219.177]:37492 "EHLO mail-ew0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756274AbZCOT44 (ORCPT ); Sun, 15 Mar 2009 15:56:56 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=bg1HRrPODeayGdJfNkDArQ9Xvq2mN0huNCJa0wcB54kjYDsM3lxO/THAReBPA51LXE hzvLiK7m7JuoAOepj+75zFwY/Ak/nz7WPNFiRRmKHCInOv4YYk/+R7trHIfR+kCFs26F hIMZUBWtntQ13EpXBKsp7Miti2ddXuoGpFb34= Date: Sun, 15 Mar 2009 20:56:50 +0100 From: Frederic Weisbecker To: Mathieu Desnoyers Cc: Ingo Molnar , akpm@linux-foundation.org, Steven Rostedt , LKML , Andi Kleen , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Subject: Re: [RFC patch 19/21] LTTng Linux Kernel Trace Thread Flag x86 Message-ID: <20090315195649.GA5212@nowhere> References: <20090315190340.229569867@polymtl.ca> <20090315191105.269978012@polymtl.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090315191105.269978012@polymtl.ca> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 15, 2009 at 03:03:59PM -0400, Mathieu Desnoyers wrote: > Add a thread flag to activate system-wide syscall tracing. > > Make x86_64 support TIF_SYSCALL_TRACE async flag set in entry.S x86-32 :-) > When the flag is inactive upon syscall entry and concurrently activated before > exit, we seem to reach a state where the top of stack is incorrect upon return > to user space. > > Fix this by fixing the top of stack and jumping to int_ret_from_sys_call if we > detect that thread flags has been modified. I don't see where you do that. May be you forgot some parts that match your changelog? > > We make sure that the thread flag read is coherent between our new test and the ALLWORK_MASK test by first saving it in a register used for both comparisons. Ditto. Thanks, Frederic. > > Signed-off-by: Mathieu Desnoyers > CC: Andi Kleen > CC: Thomas Gleixner > CC: Ingo Molnar > CC: H. Peter Anvin > --- > arch/x86/include/asm/thread_info.h | 9 ++++++--- > arch/x86/kernel/entry_32.S | 3 ++- > 2 files changed, 8 insertions(+), 4 deletions(-) > > Index: linux-2.6-lttng/arch/x86/include/asm/thread_info.h > =================================================================== > --- linux-2.6-lttng.orig/arch/x86/include/asm/thread_info.h 2009-01-14 22:10:38.000000000 -0500 > +++ linux-2.6-lttng/arch/x86/include/asm/thread_info.h 2009-01-14 22:25:08.000000000 -0500 > @@ -79,6 +79,7 @@ struct thread_info { > #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ > #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ > #define TIF_SECCOMP 8 /* secure computing */ > +#define TIF_KERNEL_TRACE 9 /* kernel trace active */ > #define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */ > #define TIF_NOTSC 16 /* TSC is not accessible in userland */ > #define TIF_IA32 17 /* 32bit process */ > @@ -102,6 +103,7 @@ struct thread_info { > #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) > #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) > #define _TIF_SECCOMP (1 << TIF_SECCOMP) > +#define _TIF_KERNEL_TRACE (1 << TIF_KERNEL_TRACE) > #define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY) > #define _TIF_NOTSC (1 << TIF_NOTSC) > #define _TIF_IA32 (1 << TIF_IA32) > @@ -117,17 +119,18 @@ struct thread_info { > > /* work to do in syscall_trace_enter() */ > #define _TIF_WORK_SYSCALL_ENTRY \ > - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | \ > + (_TIF_SYSCALL_TRACE | _TIF_KERNEL_TRACE | _TIF_SYSCALL_EMU | \ > _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | _TIF_SINGLESTEP) > > /* work to do in syscall_trace_leave() */ > #define _TIF_WORK_SYSCALL_EXIT \ > - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP) > + (_TIF_SYSCALL_TRACE | _TIF_KERNEL_TRACE | _TIF_SYSCALL_AUDIT | \ > + _TIF_SINGLESTEP) > > /* work to do on interrupt/exception return */ > #define _TIF_WORK_MASK \ > (0x0000FFFF & \ > - ~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \ > + ~(_TIF_SYSCALL_TRACE|_TIF_KERNEL_TRACE|_TIF_SYSCALL_AUDIT| \ > _TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU)) > > /* work to do on any return to user space */ > Index: linux-2.6-lttng/arch/x86/kernel/entry_32.S > =================================================================== > --- linux-2.6-lttng.orig/arch/x86/kernel/entry_32.S 2009-01-14 22:22:40.000000000 -0500 > +++ linux-2.6-lttng/arch/x86/kernel/entry_32.S 2009-01-14 22:25:44.000000000 -0500 > @@ -571,7 +571,8 @@ END(syscall_trace_entry) > # perform syscall exit tracing > ALIGN > syscall_exit_work: > - testb $_TIF_WORK_SYSCALL_EXIT, %cl > + /* Note, _TIF_KERNEL_TRACE is bit number 9, and so it needs testw and not testb */ > + testw $_TIF_WORK_SYSCALL_EXIT, %cx > jz work_pending > TRACE_IRQS_ON > ENABLE_INTERRUPTS(CLBR_ANY) # could let syscall_trace_leave() call > > -- > Mathieu Desnoyers > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68