From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
npiggin@gmail.com, segher@kernel.crashing.org
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] powerpc/uaccess: Use flexible addressing with __put_user()/__get_user()
Date: Wed, 12 Aug 2020 14:32:51 +0200 [thread overview]
Message-ID: <0b63e2b8-a134-9a50-2106-8ff110cf9a31@csgroup.eu> (raw)
In-Reply-To: <c827fd9b-984d-ca86-67e9-512ca10d118f@csgroup.eu>
Le 08/07/2020 à 06:49, Christophe Leroy a écrit :
>
>
> Le 07/07/2020 à 21:02, Christophe Leroy a écrit :
>>
>>
>> Le 07/07/2020 à 14:44, Christophe Leroy a écrit :
>>>
>>>
>>> Le 30/06/2020 à 03:19, Michael Ellerman a écrit :
>>>> Michael Ellerman <mpe@ellerman.id.au> writes:
>>>>> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>>>>>> Hi Michael,
>>>>>>
>>>>>> I see this patch is marked as "defered" in patchwork, but I can't see
>>>>>> any related discussion. Is it normal ?
>>>>>
>>>>> Because it uses the "m<>" constraint which didn't work on GCC 4.6.
>>>>>
>>>>> https://github.com/linuxppc/issues/issues/297
>>>>>
>>>>> So we should be able to pick it up for v5.9 hopefully.
>>>>
>>>> It seems to break the build with the kernel.org 4.9.4 compiler and
>>>> corenet64_smp_defconfig:
>>>
>>> Most likely a GCC bug ?
>>>
>>> It seems the problem vanishes with patch
>>> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/173de3b659fa3a5f126a0eb170522cccd909950f.1594125164.git.christophe.leroy@csgroup.eu/
>>>
>>
>> Same kind of issue in signal_64.c now.
>>
>> The following patch fixes it:
>> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/810bd8840ef990a200f58c9dea9abe767ca02a3a.1594146723.git.christophe.leroy@csgroup.eu/
>>
>>
>
> This time I confirm, with the two above mentioned patches, it builds OK
> with 4.9, see
> http://kisskb.ellerman.id.au/kisskb/head/810bd8840ef990a200f58c9dea9abe767ca02a3a/
>
>
I see you've merged those patches that make the issue disappear, yet not
this patch yet. I guess you are still a bit chilly about it, so I split
it in two parts for you to safely take patch 1 as soon as possible while
handling the "m<>" constraint subject more carefully via
https://github.com/linuxppc/issues/issues/297 in a later stage.
Anyway, it seems that GCC doesn't make much use of the "m<>" and the
pre-update form. Most of the benefit of flexible addressing seems to be
achieved with patch 1 ie without the "m<>" constraint and update form.
Christophe
next prev parent reply other threads:[~2020-08-12 12:33 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 12:39 [PATCH v2] powerpc/uaccess: Use flexible addressing with __put_user()/__get_user() Christophe Leroy
2020-06-29 6:52 ` Christophe Leroy
2020-06-29 11:27 ` Michael Ellerman
2020-06-30 1:19 ` Michael Ellerman
2020-06-30 14:55 ` Christophe Leroy
2020-06-30 16:33 ` Segher Boessenkool
2020-06-30 18:53 ` Christophe Leroy
2020-06-30 21:18 ` Segher Boessenkool
2020-07-01 7:05 ` Christophe Leroy
2020-07-07 12:44 ` Christophe Leroy
2020-07-07 19:02 ` Christophe Leroy
2020-07-08 4:49 ` Christophe Leroy
2020-08-12 12:32 ` Christophe Leroy [this message]
2020-08-12 19:30 ` Segher Boessenkool
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