Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754651AbYFRQv1 (ORCPT ); Wed, 18 Jun 2008 12:51:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752309AbYFRQvS (ORCPT ); Wed, 18 Jun 2008 12:51:18 -0400 Received: from saraswathi.solana.com ([198.99.130.12]:44589 "EHLO saraswathi.solana.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752214AbYFRQvS (ORCPT ); Wed, 18 Jun 2008 12:51:18 -0400 Date: Wed, 18 Jun 2008 12:49:42 -0400 From: Jeff Dike To: Renzo Davoli Cc: LKML , Roland McGrath Subject: Re: [PATCH 0/1] ptrace_vm: let us simplify the code for ptrace and add useful features for VM Message-ID: <20080618164942.GC8225@c2.user-mode-linux.org> References: <20080616075804.GA6950@cs.unibo.it> <20080617162511.GA7223@c2.user-mode-linux.org> <20080617190831.GC32418@cs.unibo.it> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080617190831.GC32418@cs.unibo.it> 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: 1630 Lines: 41 On Tue, Jun 17, 2008 at 09:08:31PM +0200, Renzo Davoli wrote: > 0 -> do the syscall and notify after it To be more precise - do the call notification, do the syscall, and do the return notification > PTRACE_VM_SKIPEXIT -> do the syscall and do not notify after it don't do the return notification > PTRACE_VM_SKIPCALL -> skip everything. don't do the syscall or return notification Looking at things this way, it seems like you might want three flags, since the asymmetry is caused by two things being bundled into SKIPCALL. If you have PTRACE_VM_SKIPEXIT - skip the return notification PTRACE_VM_SKIPCALL - skip the syscall PTRACE_VM_SKIPSTART - skip the call notification this makes the meaning make more sense to me. The downside of this is that you end up at least one combination that doesn't make too much sense, like PTRACE_VM_SKIPCALL (do both notifications even though nothing could have changed in between). > umview (and now kmview using a kernel module based on utrace) decides if > a syscall must be virtualized or not depending on the value of its > arguments, not on the syscall number. With "system call" I mean "call of > a system call", a "system call call";-) OK, if you're looking at the arguments in order to decide what to do, then you can't just mask out the notifications. Jeff -- Work email - jdike at linux dot intel dot com -- 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/