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>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v1 4/9] powerpc/vdso: Remove unnecessary ifdefs in vdso_pagelist initialization
Date: Fri, 28 Aug 2020 07:46:04 +0200 [thread overview]
Message-ID: <e885d2cf-4b29-95d7-38ac-bff2951e57ad@csgroup.eu> (raw)
In-Reply-To: <e9795fb5-81bc-5707-79d6-42d9dddf7ac4@csgroup.eu>
Le 28/08/2020 à 07:40, Christophe Leroy a écrit :
>
>
> Le 27/08/2020 à 15:19, Michael Ellerman a écrit :
>> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>>> On 08/26/2020 02:58 PM, Michael Ellerman wrote:
>>>> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>>>>> diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
>>>>> index daef14a284a3..bbb69832fd46 100644
>>>>> --- a/arch/powerpc/kernel/vdso.c
>>>>> +++ b/arch/powerpc/kernel/vdso.c
>>>>> @@ -718,16 +710,14 @@ static int __init vdso_init(void)
>>>> ...
>>>>> -
>>>>> -#ifdef CONFIG_VDSO32
>>>>> vdso32_kbase = &vdso32_start;
>>>>> /*
>>>>> @@ -735,8 +725,6 @@ static int __init vdso_init(void)
>>>>> */
>>>>> vdso32_pages = (&vdso32_end - &vdso32_start) >> PAGE_SHIFT;
>>>>> DBG("vdso32_kbase: %p, 0x%x pages\n", vdso32_kbase,
>>>>> vdso32_pages);
>>>>> -#endif
>>>>
>>>> This didn't build for ppc64le:
>>>>
>>>>
>>>> /opt/cross/gcc-8.20_binutils-2.32/powerpc64-unknown-linux-gnu/bin/powerpc64-unknown-linux-gnu-ld:
>>>> arch/powerpc/kernel/vdso.o:(.toc+0x0): undefined reference to
>>>> `vdso32_end'
>>>>
>>>> /opt/cross/gcc-8.20_binutils-2.32/powerpc64-unknown-linux-gnu/bin/powerpc64-unknown-linux-gnu-ld:
>>>> arch/powerpc/kernel/vdso.o:(.toc+0x8): undefined reference to
>>>> `vdso32_start'
>>>> make[1]: *** [/scratch/michael/build/maint/Makefile:1166:
>>>> vmlinux] Error 1
>>>> make: *** [Makefile:185: __sub-make] Error 2
>>>>
>>>> So I just put that ifdef back.
>>>>
>>>
>>> The problem is because is_32bit() can still return true even when
>>> CONFIG_VDSO32 is not set.
>>
>> Hmm, you're right. My config had CONFIG_COMPAT enabled.
>>
>> But that seems like a bug, if someone enables COMPAT on ppc64le they are
>> almost certainly going to want VDSO32 as well.
>>
>> So I think I'll do a lead up patch as below.
>
> Ah yes, and with that then no need to consider the case where
> is_32bit_task() is true and CONFIG_VDSO32 is not selected.
>
> I'll update my leading series accordingly.
I meant follow up series.
Christophe
>
> Christophe
>
>>
>> cheers
>>
>> diff --git a/arch/powerpc/platforms/Kconfig.cputype
>> b/arch/powerpc/platforms/Kconfig.cputype
>> index d4fd109f177e..cf2da1e401ef 100644
>> --- a/arch/powerpc/platforms/Kconfig.cputype
>> +++ b/arch/powerpc/platforms/Kconfig.cputype
>> @@ -501,13 +501,12 @@ endmenu
>> config VDSO32
>> def_bool y
>> - depends on PPC32 || CPU_BIG_ENDIAN
>> + depends on PPC32 || COMPAT
>> help
>> This symbol controls whether we build the 32-bit VDSO. We
>> obviously
>> want to do that if we're building a 32-bit kernel. If we're
>> building
>> - a 64-bit kernel then we only want a 32-bit VDSO if we're
>> building for
>> - big endian. That is because the only little endian
>> configuration we
>> - support is ppc64le which is 64-bit only.
>> + a 64-bit kernel then we only want a 32-bit VDSO if we're also
>> enabling
>> + COMPAT.
>> choice
>> prompt "Endianness selection"
>>
next prev parent reply other threads:[~2020-08-28 5:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 13:53 [PATCH v1 1/9] powerpc/vdso: Remove BUG_ON() in vdso_init() Christophe Leroy
2020-08-25 13:54 ` [PATCH v1 2/9] powerpc/vdso: Remove get_page() in vdso_pagelist initialization Christophe Leroy
2020-08-25 13:54 ` [PATCH v1 3/9] powerpc/vdso: Remove NULL termination element in vdso_pagelist Christophe Leroy
2020-08-25 13:54 ` [PATCH v1 4/9] powerpc/vdso: Remove unnecessary ifdefs in vdso_pagelist initialization Christophe Leroy
2020-08-26 14:58 ` Michael Ellerman
2020-08-26 15:21 ` Christophe Leroy
2020-08-27 6:47 ` Christophe Leroy
2020-08-27 13:19 ` Michael Ellerman
2020-08-28 5:40 ` Christophe Leroy
2020-08-28 5:46 ` Christophe Leroy [this message]
2020-08-25 13:54 ` [PATCH v1 5/9] powerpc/vdso: move to _install_special_mapping() and remove arch_vma_name() Christophe Leroy
2020-08-25 13:54 ` [PATCH v1 6/9] powerpc/vdso: Provide vdso_remap() Christophe Leroy
2020-08-25 13:54 ` [PATCH v1 7/9] powerpc/vdso: Move vdso datapage up front Christophe Leroy
2020-08-25 13:54 ` [PATCH v1 8/9] powerpc/vdso: Remove __kernel_datapage_offset and simplify __get_datapage() Christophe Leroy
2020-08-25 13:54 ` [PATCH v1 9/9] powerpc/vdso: Remove unused \tmp param in __get_datapage() Christophe Leroy
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