[PATCH] binfmt_flat: Remove shared library support

[Rich Felker]

On Wed, Apr 20, 2022 at 09:17:22AM -0700, Palmer Dabbelt wrote:
> On Wed, 20 Apr 2022 07:58:03 PDT (-0700), ebiederm at xmission.com wrote:
> >
> >In a recent discussion[1] it was reported that the binfmt_flat library
> >support was only ever used on m68k and even on m68k has not been used
> >in a very long time.
> >
> >The structure of binfmt_flat is different from all of the other binfmt
> >implementations becasue of this shared library support and it made
> >life and code review more effort when I refactored the code in fs/exec.c.
> >
> >Since in practice the code is dead remove the binfmt_flat shared libarary
> >support and make maintenance of the code easier.
> >
> >[1] https://lkml.kernel.org/r/81788b56-5b15-7308-38c7-c7f2502c4e15@linux-m68k.org
> >Signed-off-by: "Eric W. Biederman" <ebiederm at xmission.com>
> >---
> >
> >Can the binfmt_flat folks please verify that the shared library support
> >really isn't used?
> 
> I don't actually know follow the RISC-V flat support, last I heard it was still
> sort of just in limbo (some toolchain/userspace bugs th at needed to be sorted
> out).  Damien would know better, though, he's already on the thread.  I'll
> leave it up to him to ack this one, if you were even looking for anything from
> the RISC-V folks at all (we don't have this in any defconfigs).

For what it's worth, bimfmt_flat (with or without shared library
support) should be simple to implement as a binfmt_misc handler if
anyone needs the old shared library support (or if kernel wanted to
drop it entirely, which I would be in favor of). That's how I handled
old aout binaries I wanted to run after aout was removed: trivial
binfmt_misc loader.

Rich