Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754705Ab0D1DAN (ORCPT ); Tue, 27 Apr 2010 23:00:13 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:58225 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754118Ab0D1DAL (ORCPT ); Tue, 27 Apr 2010 23:00:11 -0400 Date: Wed, 28 Apr 2010 08:30:04 +0530 From: Ananth N Mavinakayanahalli To: Masami Hiramatsu Cc: Ingo Molnar , lkml , systemtap , DLE , Dave Anderson Subject: Re: [PATCH -tip 2/2] [BUGFIX] kprobes/x86: Fix removed int3 checking order Message-ID: <20100428030004.GA5541@in.ibm.com> Reply-To: ananth@in.ibm.com References: <20100427223312.2322.60512.stgit@localhost6.localdomain6> <20100427223348.2322.9112.stgit@localhost6.localdomain6> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100427223348.2322.9112.stgit@localhost6.localdomain6> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1527 Lines: 43 On Tue, Apr 27, 2010 at 06:33:49PM -0400, Masami Hiramatsu wrote: > Fix kprobe/x86 to check removed int3 when failing to get kprobe > from hlist. Since we have a time window between checking int3 > exists on probed address and getting kprobe on that address, > we can have following senario. > ------- > CPU1 CPU2 > hit int3 > check int3 exists > remove int3 > remove kprobe from hlist > get kprobe from hlist > no kprobe->OOPS! > ------- Do you have a testcase for this issue? > This patch moves int3 checking if there is no kprobe on that > address for fixing this problem as follows; > ------ > CPU1 CPU2 > hit int3 > remove int3 > remove kprobe from hlist > get kprobe from hlist > no kprobe->check int3 exists > ->rollback&retry > ------ You may also want to fix up the comment on top of kprobe_handler() about the interrupt gate as its only true for x86_32 and not x86_64, right? > Signed-off-by: Masami Hiramatsu > Cc: Ananth N Mavinakayanahalli > Cc: Dave Anderson > Cc: Ingo Molnar Acked-by: Ananth N Mavinakayanahalli -- 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/