Messages in this thread | | | Subject | Re: [PATCH v2] powerpc/uaccess: Use flexible addressing with __put_user()/__get_user() | From | Christophe Leroy <> | Date | Wed, 12 Aug 2020 14:32:51 +0200 |
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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
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