From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:48187)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <agraf@suse.de>) id 1XHERn-0005Cu-GC
	for qemu-devel@nongnu.org; Tue, 12 Aug 2014 11:57:22 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <agraf@suse.de>) id 1XHERg-0007UC-0c
	for qemu-devel@nongnu.org; Tue, 12 Aug 2014 11:57:15 -0400
Message-ID: <53EA3952.1000501@suse.de>
Date: Tue, 12 Aug 2014 17:57:06 +0200
From: Alexander Graf <agraf@suse.de>
MIME-Version: 1.0
References: <1407170739-12237-1-git-send-email-tommusta@gmail.com>
	<1407170739-12237-10-git-send-email-tommusta@gmail.com>
	<CAFEAcA_pCO_4FCpi8sXSTTqgz8vjFfOKoTuMTs1hqN_UDn_2Rg@mail.gmail.com>
In-Reply-To: <CAFEAcA_pCO_4FCpi8sXSTTqgz8vjFfOKoTuMTs1hqN_UDn_2Rg@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH 09/12] linux-user: Minimum Sig Handler
 Stack Size for PPC64 ELF V2
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Peter Maydell <peter.maydell@linaro.org>, Tom Musta <tommusta@gmail.com>
Cc: Riku Voipio <riku.voipio@linaro.org>, "qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>, QEMU Developers <qemu-devel@nongnu.org>


On 04.08.14 19:39, Peter Maydell wrote:
> On 4 August 2014 17:45, Tom Musta <tommusta@gmail.com> wrote:
>> The ELF V2 ABI for PPC64 defines MINSIGSTKSZ as 4096 bytes whereas it was
>> 2048 previously.
> Alpha and SPARC also have a 4096 byte MINSIGSTKSZ...
>
>> Signed-off-by: Tom Musta <tommusta@gmail.com>
>>
>> diff --git a/linux-user/signal.c b/linux-user/signal.c
>> index cdfcc52..b2a6e53 100644
>> --- a/linux-user/signal.c
>> +++ b/linux-user/signal.c
>> @@ -617,6 +617,15 @@ abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp)
>>       {
>>           struct target_sigaltstack *uss;
>>           struct target_sigaltstack ss;
>> +        size_t minstacksize = MINSIGSTKSZ;
>> +
>> +#if defined(TARGET_PPC64)
>> +        /* ELF V2 for PPC64 has a 4K minimum stack size for signal handlers */
>> +        struct image_info *image = ((TaskState *)thread_cpu->opaque)->info;
>> +        if (get_ppc64_abi(image) > 1) {
>> +            minstacksize = 4096;
>> +        }
>> +#endif
> Shouldn't we just define and use a TARGET_MINSIGSTKSZ ?
> Checking against the host's MINSIGSTKSZ is wrong, I think.
>
> Again, define the TARGET_MINSIGSTKSZ in a file in
> linux-user/$ARCH/, for all targets:
>   alpha, sparc, ppc64: 4096
>   everything else: 2048
> (itanium is weird here but we don't support that for linux-user guests)

and supporting ia64 is really hard, because it uses the full 64bit 
virtual address space which we can't provide on x86_64.


Alex