[Bug libc/29165] [Regression] broken argv adjustment

["adhemerval.zanella at linaro dot org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=29165

--- Comment #7 from Adhemerval Zanella <adhemerval.zanella at linaro dot org> ---
My understanding is hppa has to create the synthetic frame layout and save the
kernel passed argc/argv so the loader can proper obtain them on
_dl_sysdep_parse_arguments.  The call frame is:

  _start 
  \_ _dl_start (void *arg)
     \_ _dl_start_final (void *arg)
         \_ _dl_sysdep_start (void *arg, ...)
             \_ _dl_sysdep_parse_arguments (void **start_argptr, ...)

Once the loader setup _dl_argc and _dl_argc for the application, it does not
matter the kernel passed argc/argv (there are already processed and should not
be visible by the application).

(In reply to dave.anglin from comment #6)
> It looks to me as if _dl_start doesn't call the user entrypoint directly. 
> It calls _start in start.S. _start
> calls __libc_start_main with the argument setup shown in the comment in
> sysdeps/hppa/start.S.
> 
> On 2022-05-25 8:41 a.m., adhemerval.zanella at linaro dot org wrote:
> > https://sourceware.org/bugzilla/show_bug.cgi?id=29165
> >
> > --- Comment #5 from Adhemerval Zanella <adhemerval.zanella at linaro dot org> ---
> > But the start above will tail call _dl_start and _dl_start will call the user
> > entrypoint that will eventually calls exit syscall.  So I can't see why matter
> > restore r24 and r25 at this point, specially since they will point to the ld.so
> > ones.
> >
> > (In reply to dave.anglin from comment #4)
> >> But the comment says these are for (_start) in start.S.
> >>
> >> On 2022-05-25 7:57 a.m., adhemerval.zanella at linaro dot org wrote:
> >>> I don't think it is required since _dl_fini does not have any arguments.
> >>>
> >>> (In reply to dave.anglin from comment #2)
> >>>> Thanks.  I think we need to keep the instructions that save and restore r24
> >>>> and r25.
> >>>> They will be clobbered by call to _dl_init.
> >>>>
> >>>> Will test.

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