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

[Christophe Leroy]

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@xxxxxxxxxx> writes:
> > > On 08/26/2020 02:58 PM, Michael Ellerman wrote:
> > > > Christophe Leroy <christophe.leroy@xxxxxxxxxx> 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"