linux-kernel - Re: [PATCH 4/8] binfmt_elf: open code copy_siginfo_to

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Date:   Fri, 17 Apr 2020 22:06:32 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Christoph Hellwig <hch@....de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Jeremy Kerr <jk@...abs.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>
Subject: Re: [PATCH 4/8] binfmt_elf: open code copy_siginfo_to_user to
 kernelspace buffer

On Fri, Apr 17, 2020 at 8:13 PM Eric W. Biederman <ebiederm@...ssion.com> wrote:
>
> Christoph Hellwig <hch@....de> writes:
>
> > On Wed, Apr 15, 2020 at 10:20:11AM +0200, Arnd Bergmann wrote:
> >> > I'd rather keep it out of this series and to
> >> > an interested party.  Then again x32 doesn't seem to have a whole lot
> >> > of interested parties..
> >>
> >> Fine with me. It's on my mental list of things that we want to kill off
> >> eventually as soon as the remaining users stop replying to questions
> >> about it.
> >>
> >> In fact I should really turn that into a properly maintained list in
> >> Documentation/... that contains any options that someone has
> >> asked about removing in the past, along with the reasons for keeping
> >> it around and a time at which we should ask about it again.
> >
> > To the newly added x86 maintainers:  Arnd brought up the point that
> > elf_core_dump writes the ABI siginfo format into the core dump. That
> > format differs for i386 vs x32.  Is there any good way to find out
> > which is the right format when are not in a syscall?
> >
> > As far a I can tell x32 vs i386 just seems to be based around what
> > syscall table was used for the current syscall, but core dumps aren't
> > always in syscall context.
>
> I don't think this matters.  The i386 and x32 signal structures
> only differ for SIGCHLD.  The SIGCHLD signal does cause coredumps.
> So as long as we get the 32bit vs 64bit distinct correct all should be
> well.

Ok, makes sense. Thanks for taking a look into this!

      Arnd