From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-help-return-54732-listarch-gcc-help=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 24174 invoked by alias); 29 Jan 2014 07:51:38 -0000
Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-help.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-help/>
List-Post: <mailto:gcc-help@gcc.gnu.org>
List-Help: <mailto:gcc-help-help@gcc.gnu.org>
Sender: gcc-help-owner@gcc.gnu.org
Received: (qmail 24163 invoked by uid 89); 29 Jan 2014 07:51:37 -0000
Authentication-Results: sourceware.org; auth=none
X-Virus-Found: No
X-Spam-SWARE-Status: No, score=0.8 required=5.0 tests=AWL,BAYES_50,RDNS_DYNAMIC,T_FILL_THIS_FORM_SHORT autolearn=no version=3.3.2
X-HELO: mail.embedded-brains.de
Received: from host-82-135-62-35.customer.m-online.net (HELO mail.embedded-brains.de) (82.135.62.35) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 29 Jan 2014 07:51:35 +0000
Received: by mail.embedded-brains.de (Postfix, from userid 65534)	id 5194B652CFF; Wed, 29 Jan 2014 08:51:32 +0100 (CET)
Received: from [192.168.100.11] (unknown [192.168.100.11])	by mail.embedded-brains.de (Postfix) with ESMTP id A877D652CFC;	Wed, 29 Jan 2014 08:51:31 +0100 (CET)
Message-ID: <52E8B2FE.5040102@embedded-brains.de>
Date: Wed, 29 Jan 2014 07:51:00 -0000
From: Sebastian Huber <sebastian.huber@embedded-brains.de>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5
MIME-Version: 1.0
To: Ian Lance Taylor <iant@google.com>
CC: "gcc-help@gcc.gnu.org" <gcc-help@gcc.gnu.org>
Subject: Re: ColdFire and Thread-Local Storage
References: <52E7D186.4030108@embedded-brains.de> <CAKOQZ8yGOWKD3d7waw0f7ucaStHENQ16X=EMntnKBsG45JpG3w@mail.gmail.com>
In-Reply-To: <CAKOQZ8yGOWKD3d7waw0f7ucaStHENQ16X=EMntnKBsG45JpG3w@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
X-IsSubscribed: yes
X-SW-Source: 2014-01/txt/msg00117.txt.bz2

On 2014-01-28 20:15, Ian Lance Taylor wrote:
> On Tue, Jan 28, 2014 at 7:49 AM, Sebastian Huber
> <sebastian.huber@embedded-brains.de> wrote:
>>
>> it seems GCC uses this ColdFire TLS ABI:
>>
>> https://lists.debian.org/debian-68k/2007/11/msg00071.html
>>
>> Here we have a function
>>
>> void *__m68k_read_tp(void)
>>
>> which must return the thread pointer in register a0.
>>
>> I have to implement this function.  Is there a way to instruct GCC to return
>> the value in register a0 instead of d0 or do I have to use assembler to
>> implement this function?
>
> I believe that on m68k GNU/Linux a function that returns a pointer
> will normally return the value in a0.
>
> Ian
>

The function

void *__m68k_read_tp(void)
{
   const Thread_Control *executing = _Thread_Get_executing();

   return (char *) executing->Start.tls_area +
     _TLS_Get_thread_control_block_area_size((uintptr_t) _TLS_Alignment)
     + 0x7000;
}

translates to

__m68k_read_tp:
         move.l #_TLS_Alignment,%d0
         moveq #8,%d1
         move.l _Per_CPU_Information+18,%a0
         cmp.l %d0,%d1
         jls .L2
         moveq #8,%d0
.L2:
         add.l #28672,%d0
         add.l 194(%a0),%d0
         rts

I use now:

void __m68k_read_tp(void)
{
   const Thread_Control *executing = _Thread_Get_executing();
   void *tp = (char *) executing->Start.tls_area +
     _TLS_Get_thread_control_block_area_size((uintptr_t) _TLS_Alignment)
     + 0x7000;

   __asm__ volatile (
     "move.l %0, %%a0"
     :
     : "d" (tp)
   );
}

-- 
Sebastian Huber, embedded brains GmbH

Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone   : +49 89 189 47 41-16
Fax     : +49 89 189 47 41-09
E-Mail  : sebastian.huber@embedded-brains.de
PGP     : Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.