From owner-freebsd-hackers@FreeBSD.ORG  Wed Jul 24 18:33:57 2013
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: hackers@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTP id 5BA925EA
 for <hackers@FreeBSD.org>; Wed, 24 Jul 2013 18:33:57 +0000 (UTC)
 (envelope-from avg@FreeBSD.org)
Received: from citadel.icyb.net.ua (citadel.icyb.net.ua [212.40.38.140])
 by mx1.freebsd.org (Postfix) with ESMTP id A35662449
 for <hackers@FreeBSD.org>; Wed, 24 Jul 2013 18:33:56 +0000 (UTC)
Received: from porto.starpoint.kiev.ua (porto-e.starpoint.kiev.ua
 [212.40.38.100])
 by citadel.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id VAA25370;
 Wed, 24 Jul 2013 21:33:46 +0300 (EEST)
 (envelope-from avg@FreeBSD.org)
Received: from localhost ([127.0.0.1])
 by porto.starpoint.kiev.ua with esmtp (Exim 4.34 (FreeBSD))
 id 1V23sg-0008mY-2y; Wed, 24 Jul 2013 21:33:46 +0300
Message-ID: <51F01DD2.6060308@FreeBSD.org>
Date: Wed, 24 Jul 2013 21:32:50 +0300
From: Andriy Gapon <avg@FreeBSD.org>
User-Agent: Mozilla/5.0 (X11; FreeBSD amd64;
 rv:17.0) Gecko/20130708 Thunderbird/17.0.7
MIME-Version: 1.0
To: Yuri <yuri@rawbw.com>
Subject: Re: DTrace copyin with struct doesn't work?
References: <51F01940.2020402@rawbw.com>
In-Reply-To: <51F01940.2020402@rawbw.com>
X-Enigmail-Version: 1.5.1
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Cc: FreeBSD Hackers <hackers@FreeBSD.org>
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 24 Jul 2013 18:33:57 -0000

on 24/07/2013 21:13 Yuri said the following:
> This simple .d script fails:
> 
> ---script begin---
> #!/usr/sbin/dtrace -s
> 
> struct my_args {
>    int ii;
> };
> 
> fbt::sys_select:entry
> {
>   printf("sys_select %i", ((struct my_args*)copyin(arg1, sizeof (struct
> my_args)))->ii);
> }
> ---script end---
> 
> dtrace: error on enabled probe ID 1 (ID 33598: fbt:kernel:sys_select:entry):
> invalid address (0xffffff82ff0799d8) in action #1 at DIF offset 40
> dtrace: error on enabled probe ID 1 (ID 33598: fbt:kernel:sys_select:entry):
> invalid address (0xffffff82fefb19d8) in action #1 at DIF offset 40
> 
> Function sys_select is defined in kern/sys_generic.c:
> int
> sys_select(struct thread *td, struct select_args *uap)

>From sys_select code it is clear that uap points to something that is already
copied in.  Unlike some fields within select_args.

> arg1 in DTrace script should correspond to uap argument of sys_select, and
> dereferencing should always produce an int.


-- 
Andriy Gapon