Re: [PATCH v4 1/2] module: add elf_check_module_arch for module specific elf arch checks

[Jessica Yu]

+++ Nicholas Piggin [16/06/21 11:18 +1000]:
> Excerpts from Jessica Yu's message of June 15, 2021 10:17 pm:
> > +++ Nicholas Piggin [15/06/21 12:05 +1000]:
> > > Excerpts from Jessica Yu's message of June 14, 2021 10:06 pm:
> > > > +++ Nicholas Piggin [11/06/21 19:39 +1000]:
> > > > > The elf_check_arch() function is used to test usermode binaries, but
> > > > > kernel modules may have more specific requirements. powerpc would like
> > > > > to test for ABI version compatibility.
> > > > >
> > > > > Add an arch-overridable function elf_check_module_arch() that defaults
> > > > > to elf_check_arch() and use it in elf_validity_check().
> > > > >
> > > > > Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > > > > [np: split patch, added changelog]
> > > > > Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> > > > > ---
> > > > > include/linux/moduleloader.h | 5 +++++
> > > > > kernel/module.c              | 2 +-
> > > > > 2 files changed, 6 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
> > > > > index 9e09d11ffe5b..fdc042a84562 100644
> > > > > --- a/include/linux/moduleloader.h
> > > > > +++ b/include/linux/moduleloader.h
> > > > > @@ -13,6 +13,11 @@
> > > > >  * must be implemented by each architecture.
> > > > >  */
> > > > >
> > > > > +// Allow arch to optionally do additional checking of module ELF header
> > > > > +#ifndef elf_check_module_arch
> > > > > +#define elf_check_module_arch elf_check_arch
> > > > > +#endif
> > > >
> > > > Hi Nicholas,
> > > >
> > > > Why not make elf_check_module_arch() consistent with the other
> > > > arch-specific functions? Please see module_frob_arch_sections(),
> > > > module_{init,exit}_section(), etc in moduleloader.h. That is, they are
> > > > all __weak functions that are overridable by arches. We can maybe make
> > > > elf_check_module_arch() a weak symbol, available for arches to
> > > > override if they want to perform additional elf checks. Then we don't
> > > > have to have this one-off #define.
> > >
> > >
> > > Like this? I like it. Good idea.
> >
> > Yeah! Also, maybe we can alternatively make elf_check_module_arch() a
> > separate check entirely so that the powerpc implementation doesn't
> > have to include that extra elf_check_arch() call. Something like this maybe?
>
> Yeah we can do that. Would you be okay if it goes via powerpc tree? If
> yes, then we should get your Ack (or SOB because it seems to be entirely
> your patch now :D)

This can go through the powerpc tree. Will you do another respin
of this patch? And yes, feel free to take my SOB for this one -

    Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>

Thanks!

Jessica