Re: [RFC PATCH v2 02/13] x86/um: nommu: elf loader for fdpic

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Tazaki-san,

On Tue, Nov 12, 2024 at 11:07 PM Hajime Tazaki <thehajime@gmail.com> wrote:
> On Tue, 12 Nov 2024 21:48:28 +0900,
> > On Mon, Nov 11, 2024 at 7:28 AM Hajime Tazaki <thehajime@gmail.com> wrote:
> > > As UML supports CONFIG_MMU=n case, it has to use an alternate ELF
> > > loader, FDPIC ELF loader.  In this commit, we added necessary
> > > definitions in the arch, as UML has not been used so far.  It also
> > > updates Kconfig file to use BINFMT_ELF_FDPIC under !MMU environment.
> > >
> > > Cc: Eric Biederman <ebiederm@xmission.com>
> > > Cc: Kees Cook <kees@kernel.org>
> > > Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> > > Cc: Christian Brauner <brauner@kernel.org>
> > > Cc: Jan Kara <jack@suse.cz>
> > > Cc: linux-mm@kvack.org
> > > Cc: linux-fsdevel@vger.kernel.org
> > > Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
> > > Signed-off-by: Ricardo Koller <ricarkol@google.com>
> >
> > Thanks for your patch!
> >
> > > --- a/fs/Kconfig.binfmt
> > > +++ b/fs/Kconfig.binfmt
> > > @@ -58,7 +58,7 @@ config ARCH_USE_GNU_PROPERTY
> > >  config BINFMT_ELF_FDPIC
> > >         bool "Kernel support for FDPIC ELF binaries"
> > >         default y if !BINFMT_ELF
> > > -       depends on ARM || ((M68K || RISCV || SUPERH || XTENSA) && !MMU)
> > > +       depends on ARM || ((M68K || RISCV || SUPERH || UML || XTENSA) && !MMU)
> >
> > s/UML/X86/?
>
> I guess the fdpic loader can be used to X86, but this patchset only
> adds UML to be able to select it.  I intended to add UML into nommu
> family.

While currently x86-nommu is supported for UML only, this is really
x86-specific. I still hope UML will get support for other architectures
one day, at which point a dependency on UML here will become wrong...

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds