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SubjectRe: [PATCH v1 4/9] powerpc/vdso: Remove unnecessary ifdefs in vdso_pagelist initialization
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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.

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"
>

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