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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v1 2/6] powerpc/8xx: Always pin kernel text TLB
In-Reply-To: <a726961f-f440-b553-6c46-341a860dc90a@csgroup.eu>
References: <e796c5fcb5898de827c803cf1ab8ba1d7a5d4b76.1606231483.git.christophe.leroy@csgroup.eu> <203b89de491e1379f1677a2685211b7c32adfff0.1606231483.git.christophe.leroy@csgroup.eu> <87lfe7s1j3.fsf@mpe.ellerman.id.au> <a726961f-f440-b553-6c46-341a860dc90a@csgroup.eu>
Date:   Thu, 10 Dec 2020 11:21:29 +1100
Message-ID: <87ft4ese7q.fsf@mpe.ellerman.id.au>
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Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Le 09/12/2020 =C3=A0 11:43, Michael Ellerman a =C3=A9crit=C2=A0:
>> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>>> There is no big poing in not pinning kernel text anymore, as now
>>> we can keep pinned TLB even with things like DEBUG_PAGEALLOC.
>>>
>>> Remove CONFIG_PIN_TLB_TEXT, making it always right.
>>>
>>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>>> ---
>>>   arch/powerpc/Kconfig               |  3 +--
>>>   arch/powerpc/kernel/head_8xx.S     | 20 +++-----------------
>>>   arch/powerpc/mm/nohash/8xx.c       |  3 +--
>>>   arch/powerpc/platforms/8xx/Kconfig |  7 -------
>>>   4 files changed, 5 insertions(+), 28 deletions(-)
>>>
>> ...
>>> diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
>>> index 231ca95f9ffb..19a3eec1d8c5 100644
>>> --- a/arch/powerpc/mm/nohash/8xx.c
>>> +++ b/arch/powerpc/mm/nohash/8xx.c
>>> @@ -186,8 +186,7 @@ void mmu_mark_initmem_nx(void)
>>>   	mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, false);
>>>   	mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);
>>>=20=20=20
>>> -	if (IS_ENABLED(CONFIG_PIN_TLB_TEXT))
>>> -		mmu_pin_tlb(block_mapped_ram, false);
>>> +	mmu_pin_tlb(block_mapped_ram, false);
>>>   }
>>=20
>> This broke mpc885_ads_defconfig with:
>
> :surprise:
>
> How did I get it working ? Anyway, thanks for fixing it.

No worries. I figured you must have tested with some other series(s)
applied and/or with different configs, it happens :)

cheers