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Subject: Re: [PATCH v3 2/2] powerpc/64: add stack protector support
To:     Michael Ellerman <mpe@ellerman.id.au>,
        Segher Boessenkool <segher@kernel.crashing.org>
Cc:     Russell Currey <ruscur@russell.cc>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Andrew Donnellan <andrew.donnellan@au1.ibm.com>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
References: <2b934594d21ade67a4092637cf9e6b7d2d131187.1537801613.git.christophe.leroy@c-s.fr>
 <e84d65fb4744cf8260eb2fc9474765a7f3a60573.1537801613.git.christophe.leroy@c-s.fr>
 <0797fc91-6400-2508-1cc0-4bba78aafbbb@c-s.fr>
 <d203ccfce64c8f9fd403162f2fa3807ade7f1d28.camel@russell.cc>
 <30fb4e6b-0981-c53c-a1db-94138eaad268@c-s.fr>
 <20180926092806.GM23155@gate.crashing.org>
 <284752d1-6c32-bdca-72d3-4d8616b26fbf@c-s.fr>
 <87o9ckfpek.fsf@concordia.ellerman.id.au>
From:   Christophe LEROY <christophe.leroy@c-s.fr>
Message-ID: <64ead919-df89-bd08-bdd1-4235aae9d7b2@c-s.fr>
Date:   Wed, 26 Sep 2018 13:53:51 +0200
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Le 26/09/2018 à 13:50, Michael Ellerman a écrit :
> Christophe LEROY <christophe.leroy@c-s.fr> writes:
>> Le 26/09/2018 à 11:28, Segher Boessenkool a écrit :
>>> On Wed, Sep 26, 2018 at 09:58:30AM +0200, Christophe LEROY wrote:
>>>> Segher, any idea about this problem ?
>>>
>>>>>> arch/powerpc/platforms/powermac/bootx_init.o: In function `bootx_printf':
>>>>>> /var/lib/jenkins-slave/workspace/snowpatch/snowpatch-linux-
>>>>>> sparse/linux/arch/powerpc/platforms/powermac/bootx_init.c:88:
>>>>>> undefined reference to `__stack_chk_fail_local'
>>>
>>> Are you building as PIC?  Are you linking libssp_nonshared.a?  Why not?
>>
>> Spotted, thanks.
>>
>> arch/powerpc/platforms/powermac/Makefile contains:
>>
>> CFLAGS_bootx_init.o  		+= -fPIC
> ...
>>
>> Or maybe stack protection on bootx_init doesn't make much sense and we
>> could just do the following ?
>>
>> CFLAGS_bootx_init.o  		+= -fPIC $(call cc-option, -fno-stack-protector)
> 
> That would be fine by me.

Yes, that's what I did in v4, sent a few minutes ago. Indeed the same 
was already done for prom_init, which is similar.

Christophe